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COMPETENCY-BASEDLEARNING MATERIAL

FOURTH YEAR

REPUBLIC OF THE PHILIPPINES

DEPARTMENT OF EDUCATIONPUBLIC TECHNICAL-VOCATIONAL

HIGH SCHOOLS

Unit of Competency: OPERATE FISH NURSERY

Module No.: 1 Module Title: OPERATING FISH NURSERY


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TABLE OF CONTENTS

MODULE I

What Is This Module About? ................................................................ 3What Will You Learn? .......................................................................... 3

LESSON 1.Preparing Nursery Pond ...................................................................... 4

What Is This Lesson About? ............................................................. 4What Will You Learn? ....................................................................... 4What Do You Already Know? ............................................................ 4Let Us Study .................................................................................... 5Let Us Remember ........................................................................... 15How Much Have You Learned? ....................................................... 15

Let Us Apply What You Have Learned ............................................. 17Resources ...................................................................................... 17References ..................................................................................... 17

LESSON 2.Stocking Fish In Nursery Pond .......................................................... 18

What Is This Lesson About? ........................................................... 18What Will You Learn? ..................................................................... 18What Do You Already Know? .......................................................... 18Let Us Study .................................................................................. 19Let Us Remember ........................................................................... 23

How Much Have You Learned? ....................................................... 24Let Us Apply What You Have Learned ............................................. 24Resources ...................................................................................... 24References ..................................................................................... 24

LESSON 3.Performing Feeding And Monitoring Water Quality ........................... 25

What Is This Lesson About? ........................................................... 25What Will You Learn? ..................................................................... 25What Do You Already Know? .......................................................... 25Let Us Study .................................................................................. 26

Let Us Remember ........................................................................... 34How Much Have You Learned? ....................................................... 34Let Us Apply What You Have Learned ............................................. 35Resources ...................................................................................... 35References ..................................................................................... 35

LESSON 4.Performing Awareness On Monitoring Disease And ImplementingTreatment ......................................................................................... 36

What Is This Lesson About? ........................................................... 36What Will You Learn? ..................................................................... 36

What Do You Already Know? .......................................................... 36Let Us Study .................................................................................. 37Let Us Remember ........................................................................... 44


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MODULE I

QUALIFICATION TITLE : AQUACULTURE NC II

UNIT OF COMPETENCY : OPERATE FISH NURSERY

MODULE TITLE : OPERATING FISHNURSERY

NOMINAL DURATION : 240 HOURS

WHAT IS THIS MODULE ABOUT?

This module covers the knowledge, skills and right attitudes inpreparing and stocking fishes in nursery pond, feeding, monitoring waterquality, monitoring diseases and implementing treatment, harvesting andproper post harvest handling.

WHAT WILL YOU LEARN?

After completing this module, you should be able to:

1. prepare nursery pond;

2. stock fish in nursery pond;3. perform feeding and monitor water quality;4. perform awareness on disease monitoring and implement

treatment; and5. harvest and adopt proper post-harvest handling.


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LESSON 1.

PREPARING NURSERY POND

WHAT IS THIS LESSON ABOUT?

The lesson deals with preparing productive nursery pond. Thisincludes ways of analyzing soil and water parameter, methods of applyingcomputed predators control, ways of analyzing and computing selectedfertilizer and procedures in allowing food to bloom prior to stocking.


At the end of the lesson, you should be able to:

1. prepare the pond by plowing, tilling and drying.2. compute the appropriate amount of chemicals for predator control.3. use appropriate mechanical control measures against predators

based on species of fishes.4. grow natural food in the nursery pond prior to stocking of fishes.5. analyze soil pH for appropriate quantity of lime to be applied.

WHAT DO YOU ALREADY KNOW?

Before you go through the lesson, try to answer this pre-test. Thiswill enable you to find out what you already know and what you stillneed to know about Preparing Nursery Pond. Answer this in your testnotebook.

Pre-Test

Choose the letter of the correct answer.

1. Which of the following steps in preparing a nursery pond should comefirst?a. pond dryingb. pond liming

c. pond drainingd. pond fertilization

2. The following are purposes of using lime except -a. to correct soil acidity.b. to prevent pH fluctuations in ponds.c. to produce the incidents of gill disease of fish.d. to permit normal reproduction and growth.

3. The following are the types of natural food except -a. lablab c. planktonb. lumut d. rice bran


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4. Exact liming rate is determined through -a. water analysisb. soil analysis

c. fertilization analysisd. none of the above

5. Which of the following does not belong to the group?a. pH c. temperatureb. salinity d. fertilizer

6. What are the two types of fertilizers applied in the fishpond?a. organic and inorganicb. complete and incomplete

c. single and doubled. none of the above

7. It is a method of pond fertilization wherein the fertilizer is placed insocks tide to bamboo suspended in the water.

a. platform methodb. bamboo method c. sack methodd. fertilization

8. Why is it necessary to apply fertilizer in nursery pond?a. for the production of natural food c. a and bb. to neutralize the pH value d. none of these

9. What are the microscopic animals found in fishpond water?a. phytoplankton c. planktonb. zooplankton d. lumut

10. It is a microscopic plant organism in fishpond water.a. phytoplankton c. planktonb. zooplankton d. lumut

LET US STUDY

Fish seed is an essential input for the fish farmers all over theworld. It is the basic input which can affect the production cycle. Thehigh quality fish seed are necessary to support any aquaculture system.Therefore, fish farmers must either produce their seed or depend uponseed producing farms or hatcheries.

Let Us Define

Detritusloose materials that result directly from rock disintegration.Fertilization the process of spreading, broadcasting or applying

organic or inorganic fertilizers in the pond primarily for thepurpose of providing nutrients in sufficient quantities.

Fish pond an earthen space enclosed with dikes, provided with gates,divided into several compartments where fishes are reared from fry

to marketable sizes.Fish seedfish fry that has a size of around 2 cm long or more.Limea white substance, calcium oxide used in neutralizing acid soil.


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Natural foodsminute plants or animals grown in pond bottom inducedthrough application of fertilizer in the soil or water.

Pesticideschemicals used for killing organisms, insects and weeds.Predatorsthe animals that feed on other animals.Soil analysis the process of breaking down chemical and physical

component of soil.Turbiditythe quality of water of being muddy, thick or opaque water

due to suspended soil sediments causing a darkening or obscuringof clear water.

Steps in Pond Preparation

Step 1.

Pond Draining. If gravityflow does not permit full draining,then use a pump to drain waterfrom the pond.

Figure 1. Pond Draining

Step 2.

Elimination of Fish Predators and Nuisance Weeds.Predators can be controlled using different methods:

Mechanical Removal:

Drain and dry fishpond until the pond bottom cracks.

Pick up undesirable fishes, snails and other predators.

Burrowing predators may be eliminated by allowing water toenter.

Chemical Methods:

Organic pesticides arerecommended becausethey are biodegradable.

Inorganic or chemicalpesticides are moreeffective but they maypersist in theenvironment.

Figure 2. Application of pesticide toeliminate predators


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Birds Aquatic Insects

Frog Mudfish/Dalag Catfish/Hito Biya/Goby Fish

Figure 3. Enemies of fish in freshwater ponds

Figure 4. Enemies of Fish in Brackishwater ponds

Water hyacinth (Eichornia crassipes) Quiapo (Pistia stratiotes)

Azollaa problem Giant duckweedin Banaue, Ifugao (Spirodella polyrhiza)

Figure 5. Nuisance Aquatic Weeds in Fish Ponds


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Recommendations of Chemical Pesticides

1. For eradication of polychaets worms and snails

a. Application of 0.3 ppm Bayluscide in pond water.b. Application of 0.3 ppm Shell WL 8008 (toxicity lasts for a few

days)c. Application of 0.2 ppm Aquatin in pond water or 5-8 tbsp.

Aquatin per 5 gal. of water springkled over 300-500 sq. meter ofpond area.

d. 0.1 ppm Gusathion A in pond water (wash pond thoroughlyafter treatment because toxic residues tend to persist for anumber of days).

e. Application of 400 kg/ha of tobacco dust, evenly distributed.

f.

Use 5 tons/ha of rice straw placed in heaps in ponds. Upondecay, this becomes fertilizing materials.

2. For the control of Phytoflagellates.a. Application of 2 ppm copper sulfate kept in suspension in pond

water.

3. For the elimination of fish predators or competitors and othernuisance species:a. Application of 16 ppm potassium permanganate in pond water.b. Application of 0.25 ppm potassium cyanide (toxic effects

disappear after 5 days).

Step 3.

Pond Harrowing. After one week of pesticide application, harrowthe pond to expose 5-10 cm layer of the soil. Harrowing allows organicgases in the soil to escape to the atmosphere. Use harrowing devicepulled by a carabao or hand tractor.

Figure 6. Pond Harrowing Figure 7. Drying the pond untilcracking stage


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Step 4.

Pond Drying.The pond bottom should dry out until it cracks. Thismineralizes the soil and helps in eliminating fish predators. Drying periodof a minimum of two weeks or longer is ideal depending upon the weather

and pond bottom conditions.

Purposes of pond drying:1. to eradicate fishpond pests, predators and competitors2. to hasten the chemical decomposition of organic matters deposited

so that nutrients will become available for the growth of fish food inthe fishpond

3. to totally harvest the fish stock4. to kill disease causing organism

Step 5.

Repair of Dikes, WaterInlet and Outlet Canals/Pipes.Repair any damages such as holes,cracks, etc for these will preventsoil erosion and entry of unwantedanimals inside the fishpond.

Step 6.

Vegetating Top of Dikes.Plant vegetables or non-aggressivegrasses on dikes to prevent erosionand avoid turbidity during adverseweather.

Figure 8. Repairing damages (i.e. dikes,water inlet and outlet canals/pipes)

Step 7.

Screening Water Canals/Pipes (Supply and Drainage). Screenwater supply and drainage canals/pipes using fine mesh screen (24 holesper 2.5 cm) to prevent the entry of unwanted fishes.

Figure 9. Screening Figure 10. Lime


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Step 8.

Liming. Liming is a preventive measure or remedial process toincrease alkalinity of the ponds and improve aquatic organism survival,optimize growth and ensure desirable water quality. Lime is commonly

applied on pond bottom. To achieve maximum effectivity, lime should beraked and plowed into the soil.

Methods in Controlling or Correcting Acidity:1. Leaching During the process of drying pond bottoms, acid

forming elements are exposed to air and sunlight, and by oxidationwill combine with water or forms precipitates. Acidity issignificantly reduced by washing or flushing pond bottoms. Thisprocess is effective in slightly acidic soil. In extremely acidic soil, itwill take a longer time to correct acidity.

2. LimingThere are three commonly used forms of lime:a. Unslaked lime (CaCO3 or quicklime), manufactured by heating

crushed limestone and seashells is the fastest acting form. Ithas an efficiency rating of 173% CaCO3. Its main function is tocontrol soil and water acidity, and pond pests and diseases.(Caution in handling)

b. Slaked lime (Ca(OH)2 or hydrated lime) also a burned lime withwater added has an efficiency rating of 135% CaCO3. It is alsofast acting.

c. Agricultural lime (CaCO3 or dolomitic lime) is crushed limestone

or shells. Its theoretical efficiency is less than 100%. Thismaterial is relatively slow acting but due to the low cost andease of application it may be best for long term control of soilacidity.

Procedure in Lime Application

1. Soil Analysis

The need of pond soil should be properly evaluated todetermine whether lime is needed. Then the rate of application orlime requirement must be established. Knowing the proper rate oflime application is important to prevent over liming to minimizeexpenses and possible loss of phosphate from pond waters throughthe formation of insoluble calcium compounds.

2. Application of Lime

Lime is broadcast and spread over the drained pond withbottom. The lime should be mixed with the soil to attain maximumeffectiveness. Sufficient time or about a week or two after applying

lime is allowed to elapse before the application of phosphatefertilizer.


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Several studies show that soft pond bottom with pH of 6.5has rapid growth of green and blue algae. Those with pH less than6.5 should either be washed or treated with lime depending uponthe degree of acidity. Some practical ways of determining soilacidity:

1. Identify acid problem pond -a. A newly excavated pond is likely to be acidicb. Ponds that do not respond to fertilizationc. Ponds with plenty of decaying bakawanrootsd. Pond bottom that turns reddish when exposed to sunlight for

more than three days

2. Determine the soil pH color metrically -Preparation:

Dissolve in one liter of distilled water0.8 g Bromothymol blue indicator0.4 g Methyl red powder0.2 g Methyl orange powder

Use:

Place a small quantity of soil on a white porcelain plate andmix it with several drops of the indicator then till the plate sothat excess liquid flows away from the soil. Observe the color.

Color pH

Red very acidic 4.0 or lessYellow Acidic between 5.0 and 6.0

Green 7.0 and above

Amount of lime to be used:

About ton of dolomitic limestone per hectare is needed toraise the pH by 0.1 when the soil pH is below 7.0. To calculate theamount of unslaked lime, divide the total amount by 1.73, or if slaked

lime is used divide by 1.35.

Example: Pond bottom soil pH = 6.2Desired pH = 6.5

6.5- 6.2 3 x .5 = 1.5 Tons Agricultural (dolomitic) lime

0.3 or 1.5/1.73 = 870kg unslaked limeOr 1.5/1.35 = 1100kg slaked lime


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Figure 11. Application of Lime bybroadcasting

Figure 12. Pond applied with lime

The amount of lime to be applied depends on how acidic the soil isand the texture of the soil. Response to fertilization is best when pHvalues of pond soil are brought within the range of 7.5 - 9.5.

Step 9.

Initial Filling of Water. Fillthe pond with water up to thedepth of 3050 cm. then fertilizefor initial production of naturalfood.

Step 10.

Pond fertilization topromote the growth of naturalfood. Growth of natural food reduces the cost of production. Growingnatural food in the fishpond can be done by the application of fertilizer,either organic or inorganic.

Kinds of Natural Food for fishes:

1. Plankton a collective term for microscopic organisms

(phytoplankton refers to plants; zooplankton refers to animals)suspended in water. Their motility is dependent on the movementof water. Present in freshwater and brackishwater.

2. Lumut a filamentous green grass algae such as chaetomorphalinum (lumut gusi), Cladophora species and Enteromorphaintestinalis (bitukang manok).

3. Lablaba complex association of minute plants and animals thatform a brownish, greenish or yellowish mat on the pond bottomand sometimes float on the pond surface as patches.

Figure 13. Initial water intake


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Components of lablab:Plantsblue green algae, green algae, diatoms, rotifers.Animalscrustaceans, larval, insects, round worms, detritus.

Fertilization

It is the process of spreading, broadcasting or applying organicor inorganic fertilizers in the pond primarily for the purpose ofproviding nutrients in sufficient quantities.

Types of Fertilizer as to origin:

1. Organic Fertilizer Natural Fertilizer- decomposing plants and animals forming a soft black mud.Ex: cow dung, pig manure, poultry, carabao manure,

compost, green grass, chicken manure.

2. Inorganic fertilizer - Artificial fertilizer- commercial fertilizer used in side dressing

Kinds of Inorganic fertilizer as to nutrient composition:a. Single fertilizercontains only one element

ex: Urca (45-0.0)Superphosphate (0-20-0)Ammonium sulfate (21-0-0)

b. Incomplete fertilizer - contains two elementex: Monoammonium phosphate (16-20-0)

Diamonium phosphate (18-46-0)

c. Complete fertilizer - contains all major elementsex: Triple 14 (14-14-14)

Triple 12 (12-12-12

Table 1. Suggested Fertilization Rates

Fertilizer Source Applicationrate

Organic fertilizer Chicken manure 500-1500 kg/ha

Inorganicfertilizer/Chemical

Ammonium phosphate(16-20-0)

120 kg/ha

Urea (46-0-0) andAmmonium phosphate

25 kg/ha + 50kg/ha

Inorganicfertilizer

Any source 4 kg. N/ha/da

Procedures in Propagating Lablab

1. Dry the pond bottom and expose it to sunlight.


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2. Apply chicken manure by spreading evenly over the pond bottom atthe rate of 10002000 kg/ha for new ponds (1-4 years in use) and5001500 kg/ha for ponds greater than 5 years in use.

3. Admit water to a depth of about 3-5 cm; apply 50 kg/ha Urea (46-

0-0) to hasten decomposition of the manure; and then allow thepond to dry for 3 days.

4. Re-admit water to average depth of 8-10 cm.

5. Apply 16-20-0 fertilizer at 100 kg/ha or 18-16-0 at 50 kg/ha byspreading evenly over the pond bottom the next day.

6. Admit additional 5 cm depth of water every 3 days until it reachesthe 20 cm level.

7. Apply 16-20-0 at 15 kg/ha every 7 days but not less than 3 daysbefore stocking of fish.

8. Three days before stocking, gradually drain 25 % of water and refillto the desired level of 20 30 cm (for nursery pond). Admit watergradually to avoid disturbance of lablab growth.

9. Stock fish on the 28th to 35th day from the time of spreading themanure depending on the thickness (about 1 cm) of lablab.

10.To maintain a luxuriant growth of lablab, apply a side dressing of15 kg/ha of 16-20-0 every 2 weeks during the rearing period. Stopfertilization 20 days before harvest.

Procedures in Producing Plankton

1. Fill pond with water to a depth of at least 60 cm, preferably 75-100cm.

2. Apply 1-2 tons/hectare of chicken manure by soaking it in thepond for at least 24 hours before releasing. Add 50 kg/ha Ureaafter the manure had settled down. Organic fertilization along withUrea which serves to hasten decomposition of manure could alsobe done before admission of water into pond.

3. Apply 16-20-0 at 50 kg/hectare or 22 kg/hectare of 18-46-0 oneweek after the 1stfertilizer application. One half () of this amountwill be dissolved in pail of water and spread over the pond watersurface. The other half will be put in a thin cloth bag or anysubstitute and then hang strategically on a stake positioned in thepond for gradual release of fertilizer nutrients.

4. Observe the productivity of plankton for the next 7 days throughthe green to yellowish-green turbidity of water. Visibility reading


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using a device called Secchi Disc is ideal at 30-40 cm below watersurface. Turbidity above this range indicates low planktonproductivity and signals further or additional fertilization.

5. Fish stocking shall be done 2 weeks or so after filling of water

during which time plankton growth is at 30-40 cm secchi disclevel.

6. Apply 50 kg/hectare of 16-20-0 or 29 kg/hectare of 18-46-0 every2 weeks plus 1000 kg/ha chicken manure every month thereafterto maintain the abundance of plankton. Stop fertilization 20 daysbefore harvest.

How to Apply Fertilizer?

Method A. Dissolved Fertilizer Put fertilizer particles in a pail and dissolve with water.

Apply dissolved fertilizer evenly on pond surface.Method B. Platform method

Construct a platform made of galvanized iron sheet with area of1 m x 1 m. The platform must have feet to stand in the water.

Set the platform 10-15 cm below water surface.

Put fertilizer particles on the platform and allow the fertilizer todissolve slowly.

The platform must be at the location of the pond where the waveaction as influenced by the wind can help in the distribution of

the dissolved fertilizer.Method C. Sack method

Place fertilizer in a sack and suspend in water. The sack withfertilizer must be tied to bamboos set in different locations of thepond.

The sack will be saturated with water and the fertilizer particleswill be dissolved slowly.

LET US REMEMBER

pH 6.5 - 9 is the most favorable condition for the growth of fishes.

Pond should be dried until cracking stage to totally eliminatepredators and competitors.

Fertilization accelerate the growth of natural fish food.

HOW MUCH HAVE YOU LEARNED?

Now that you have finished the lesson, letsfind out how much youhave learned from it by answering the post-test. Answer this in your testnotebook.


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Post Test

Choose the letter of the correct answer.

1. Which of the following steps in preparing a nursery pond should come

first?a. pond dryingb. pond liming

c. pond drainingd. pond fertilization

2. The following are purposes of using lime except -a. to correct soil acidity.b. to prevent pH fluctuations in ponds.c. to produce the incidents of gill disease of fish.d. to permit normal reproduction and growth.

3. The following are the types of natural food except -a. lablab c. planktonb. lumut d. rice bran

4. Exact liming rate is determined through -a. water analysisb. soil analysis

c. fertilization analysisd. none of the above

5. Which of the following does not belong to the group?a. pH c. temperatureb. salinity d. fertilizer

6. What are the two types of fertilizers applied in the fishpond?a. organic and inorganicb. complete and incomplete

c. single and doubled. none of the above

7. It is a method of pond fertilization wherein the fertilizer is placed insocks tide to bamboo suspended in the water.a. platform methodb. bamboo method

c. sack methodd. fertilization

8. Why is it necessary to apply fertilizer in nursery pond?a. for the production of natural food c. a and bb. to neutralize the pH value d. none of these

9. What are the microscopic animals found in fishpond water?a. phytoplankton c. planktonb. zooplankton d. lumut

10. It is a microscopic plant organism in fishpond water.a. phytoplankton c. planktonb. zooplankton d. lumut


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LET US APPLY WHAT YOU HAVE LEARNED

1. Practicum on the nursery pond preparation.2. Analyze soil pH for appropriate quantity of lime to be applied.3. Compute the amount of fertilizer to be applied in the fishpond.

4. Compute the amount of lime to be applied in the fishpond.5. Prepare a report on the activities done in preparing a nursery

pond.

RESOURCES

FacilitiesNursery fishpond

EquipmentWater pump

ToolSoil and water analysis kitMaterials

LimeFertilizer

REFERENCES

Cagauan, A. G. Tilapia Grow Out Systems And Operation Manual,CLSU Nueva Ejica

Operate Fish Nursery Module. Junior Agriculture Technician.

Lasam, G. D. Region 2 Technoguide for Tilapia. Department ofAgriculture-Region 2.


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LESSON 2.

STOCKING FISH IN NURSERY POND


The lesson deals with the procedures of stocking fry, controllingwater parameters and proper handling/transporting of fry andfingerlings.



1. monitor and regulate water parameter prior to stocking based onspecies requirements;

2. observe handling, transporting and stocking of the species of fishesto be cultured according to aquaculture practices;

3. determine the right quantity of fry based on stocking rate of thespecies;

4. acclimatize fry based on water temperature and salinity;5. observe the condition of fry stocked in the nursery pond based on

proper handling procedure; and6. appreciate and be able to apply the stocking techniques in stocking

fry.


Before you go through the lesson, try to answer this pre-test. Thiswill enable you to find out what you already know and what you stillneed to know about Stocking Fish in Nursery Pond. Answer this inyour test notebook.

Pre-Test

Write Ton the blank if the statement is correct. If false, write F,then underline the word/words that makes/make the statement wrongthen change to make it correct.

1. Do not expose containers/plastic bags with fish to direct sunlight.2. The best time to release the stocks is during the cooler part of the day.3. There are 10,000 square meters in one hectare.4. Oxygen is not necessary when fry are transported.5. The ideal rate of stocking fry is 30-50 fish/m2.

6. Stress caused by crowding could be the main cause of mortality.7. The quality of fish majority depend on the packing methods, materials

used and travel time.


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8. Acclimatization should be done when salinity level of the water is notthe same.

9. Acclimatization is very essential prior to feeding.10. It is not necessary to compute the stocking rate to prevent

overcrowding.

LET US STUDY

Stocking is one of the most important factors in successful fishproduction. Proper stocking assures that the maximum number of youngstock will live and grow.

In order to avoid mortality of fishes produced, the technology ofhandling and transporting has to be perfected with reference to each

species. Fry are delicate organisms, which need utmost care.

Let Us Define

Acclimatization the process of adjusting the fish to its newenvironment

Depletionthe loss or lacking of one thingFingerling a young fish much bigger than fry and generally around 2

inchesFrya newly hatched fish attaining a size of around 2 cm long or more

Hectareequivalent to 10,000 m2Stockingthe process of releasing fish in the culture facilitiesStocking ratethe number of fish to be stocked in the culture facilitiesPhotosynthesis the formation of carbohydrates in living plants from

the water and carbon dioxide by means of sunlight on theapplication of organic and inorganic fertilizer

Cannibalsanimals that eat their own kindTemperaturethe overall hotness and coldness of waterSalinitythe amount of salt present in the water as expressed in parts

per thousand (ppt)Stock

cultured or raised fish

Monitoring and regulating water parameter

1.TemperatureTemperature is critical during stocking of fish. Sudden changes intemperature can result to mortality in aquatic animals. Optimumwater temperature for nile tilapia is 28-35 oC. A laboratorythermometer is used to monitor the appropriate water temperatureduring stocking.

2. Dissolved Oxygen


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All fishes regardless of species and culture conditions need oxygenfor growth and survival. Lock of oxygen results in poor growth andout break of diseases of mortality. Generally, most warm waterspecies of fish need dissolved oxygen at a level of one part permillion (ppm) for survival and about 3 ppm for comfort. Dissolved

oxygen of five part per million is the most ideal for growth andexcellent in maintaining fish health.

Stocking Techniques and Practices

1. Stock the pond only when the plankton or lumut are stretchedstraight to at least 30 centimeters high. This is a sign that there issufficient food for young stock to nourish them during the growingperiod.

2. Do not stock the pond when the parameters are not yet favorablefor the growth of fingerlings. If a special device to assess thecondition of dissolved oxygen, temperature, and salinity of water isunavailable, check the growth of plankton to determine the pondswater conditions.

3. Stocking should be done in the evening, early in the morning orlate in the afternoon to ensure that the temperature of pond wateris not too hot and to enable the fish to acclimatize easily. Impropertemperature may cause sudden death among fingerlings.

4. Acclimatize the fish to their new habitat by floating the plastic bagcontaining young stock in the pond water for at least 30 minutesbefore finally transferring the stock to their new environment.

5. If the temperature and salinity of the pond water and water in theplastic bag greatly varies, introduce pond water gradually into theplastic bag at least two to four times the original volume of waterbefore finally releasing the fingerlings or fish fry.

6. Distribute the fish fry or young stock throughout the whole pondas uniformly as possible. Overcrowding may result to stuntedgrowth of fish, physical injuries and mortality.

Stocking Rate

Stocking rate in the nursery ponds depends on water management,availability of food and system of culture. One hectare of nursery pondwith good growth of lablab may be capable of supporting around 300,000fish fry or a rate of 30-50 fry/m2but commercial nursery operators stock

as high as 100 fry/m2.

Computation involving Fish Stocking


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Formula:

No. of Stocks = Area x Stocking rate per unit area

Example:

If the standard rate of stocking is 50/square meter, how many fish will beneeded to stock in a 20 m x 50 m pond?

Solution:I. Determine the area if such is not given or is unknown

20 m x 50 m = 1000 m2

II. Solve for the number of stocks using the formula above.No. of stocks = Area x Stocking rate per unit area

= 1000 m2x 50/m2

= 50,000 fish

Fry Transport

Pointers to consider in transporting fry

1.Transfer or carry all the bags to the transport vehicle piling them oneat a time.

2. Fasten the bags with any tying material from rolling/mixing while in

transit.

Figure 1. Piled bags inside

transport vehicle

Figure 2. Piled bags in transportation

fastened with tying materials

3. Place cracked ice on top of bags. This lowers water temperature.

4. Cover the bag with canvas or anything to protect from exposure tosunlight.

Figure 3. Ice chuck on top of the bags

Figure 4. Bags covered with canvas


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5. When you arrive at the site, remove the plastic bags inside the pandanbag and put it on the water to float for at least 5 minutes. This willallow the fry to adjust themselves to the temperature of the pond

water.

Figure 5. Bags under shade. Figure 6. Bags floating in pond waterto acclimatize.

6. Open the bags by removing the rubber band and allow pond water toenter the bag gradually. This facilitates gradual adjustment of fry tosalinity and other conditions of water.

7. Release all fishes in the pond by tilting the plastic bags slowly for thefish to swim out freely.

8. Collect, clean and fold all polyethylene bags and pandan for storage.

Figure 7. Bags opened releasing fry into the pond.

Figure 8. Relationship of DO in a certain time of the day

24-hr DO profile

6 am 12 noon 6 pm 12 mid

DO m /l


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3. Hydrogen ion Concentration (pH). The pH of the water determine itsacidity and alkalinity. The ideal pH range of the water where stocking fryor fingerlings 6.59.

Measure pH with the use of litmus paper, pH comparator, portablepH makers or the Hack kit. In the absence of any of these equipment,tasting the water is a practical way to determine the pH. The water isacidic if it tastes sour and if it tastes bitter it is alkaline. Liming andcorrect water management correct pH in pond water

Figure 9. pH range at a certain time of the day

4. Salinity

It can be measured with the use of hydrometer orrefractometer. A hydrometer is simple and inexpensive. Salinity isdetermined by collecting small amount of pond water where thehydrometer is floated. A refractometer is an expensive device butvery useful. With a drop of pond water place on the refractometer,the salinity can be determined through direct reading.

Salinity can drop easily to almost fresh water during rainydays. It is therefore necessary to allow as much tidal water to the

pond as possible where rain will be expected. This will minimizedilution or abrupt lowering of salinity when heavy rain falls.Usually rain water will stay on the top level of the pond so excesswater should be overflowed over the gate boards.

LET US REMEMBER

The best time for stocking fry/fingerlings is during early morningor late in the afternoon.

Use only stress-free, healthy stocks that meet high quality

standards for primary and secondary species. It is important to acclimatize the fish stocks before releasing them

in culture facilities.

24-hr H

6 am 12 noon 6 pm 12 mid

pH


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Now that you have finished the lesson, lets find out how much youhave learned from it by answering the post-test. Answer this in your testnotebook.

Post Test

Write Ton the blank if the statement is correct. If false, write F,then underline the word/words that makes/make the statement wrongthen change to make it correct.

1. Do not expose containers/bags with fish to direct sunlight.2. The best time to release the stocks is during the cooler part of the day.3. There are 10,000 square meters in one hectare.

4. Oxygen is not necessary when fry are transported.5. The ideal rate of stocking fry is 30-50 fish/m2.6. Stress caused by crowding could be the main cause of mortality.7. The quality of fish majority depend on the packing methods, materials

used and travel time.8. Acclimation should be done when salinity level of the water is not the

same.9. Acclimatization is very essential prior to feeding.10. It is not necessary to compute the stocking rate to prevent

overcrowding.


1. Stock the fry/fingerlings based on acclimatization procedures.2. Compute the stocking based on the area of the fishpond.3. Observed handling, transporting and stocking of fish to be

cultured.

RESOURCES

FacilitiesFishpond

MaterialsFry/fingerlingsPolyethylene bagRubber

ToolsOxygen tankSecchi discpH meterDO meterRefractometer /Hydrometer

REFERENCES

Cagauan, A. G. Tilapia Grow Out System and OperatonFernandez, P. Fishery Arts for Secondary Schools Exporatory.

Schmittou H.R. Principles and Practices of 80:20 Pond FishFarming. International Center for Aquaculture and AquaticEnvironments.


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LESSON 3.

PERFORMING FEEDING ANDMONITORING WATER QUALITY


The lesson deals with feeding and monitoring water quality. Thisinclude ways of sustaining the growth of natural food, ways of samplingand analyzing formulated feed for feed ration, methods of computingdaily feed ration and procedures of changing water regularly to maintainthe good water quality.



1. process and store feeds properly;2. sample and analyze formulated feed for feed ration;3. compute the daily feed ration based on fish biomass;4. observe proper feeding based on their feeding requirement; and5. conduct changing of water regularly based on water condition.


Before you go through this lesson, try to answer this pre-test. Thiswill enable you to find out what you already know and what you stillneed to know about Performing Feeding and Monitoring WaterQuality.Answer this in your test notebook.

Pre-Test

Write T on the blank if the statement is correct. If false, write F,then underline the word/words that makes the statement wrong then

change to make it correct.

1. Storage condition should be optimal to avoid deterioration of feedingredients.

2. Relative humidity of less than 65% promotes fungal growth and insectinfestation.

3. Low temperature destroys or reduces the availability of feed nutrients.4. Biomass is the total weight of fish per unit area at a particular time.5. Frequent feeding is recommended when fish are small, when natural

food is inadequate.6. Good water quality enhances fish growth and minimizes mortality.

7. Low tide is the ideal time of changing pond water.8. Soil sealing the pond gate prevents leakages.9. Proper storage sanitation is not necessary.


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10. Increase feeding rate when natural food production is high.

LET US STUDY

Feeds for fish intensively cultured in ponds must be nutritionally

complete and should be nutritionally balanced. Although someomnivorous fish, such as nile tilapia, may obtain some essentialnutrients by filtering plankton from nutrient rich waters. They still needa complete diet as if they are being cultured in food-free waters.

The objective of feeding fish is to provide the nutritionalrequirements for good health, optimum growth, optimum yield, andminimum waste and at reasonable cost for maximum profit.

Let Us Define

Biomass- the total weight of fish per unit area at a particular time and isexpressed as kg/ha, kg/sq.m., or g/sq.m.

Feeds - foods given to animal.Feeding frequency- the number of times fish are fed in a day.Feeding rate- the amount of feeds given daily to culture stock expressed

as percentage of stock biomass.Rancidity- something smells off flavors.Plankton - microscopic organisms that serve as food for the fishes.Lablab- a complex association of minute plants and animals.

Processing and Preparation of Feedstuff

Processing and preparation refers to all the operations necessary toobtain the highest nutritional value of a feedstuff and the best economicreturns from their use. The processing of feedstuffs accomplishes severalpurposes:

1. It removes anti-nutritional factors and toxins.2. It lowers the moisture content of feedstuff to 10% less.3. It adjusts feed particles size to suit a given species and size,

and reduce waste of feed4. It increases palatability and nutrient availability.5. It maximizes profit through optimum processing of feeds.

Excessive heat treatment or extraction under alkaline conditionsmay lead to the destruction or alternation of amino acids. In effect, theprotein becomes biologically unavailable. The effects of soaking, dehullingand solvent extraction on the nutritive value of protein have yet to beclarified.

Soaking

Soaking facilitates cooking or removes some toxins especially fromplant sources. Feedstuffs are usually soaked in water for 6-24 h at room


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temperature. For example, ipil-ipil leaves are soaked for 24 h to removemimosine and leguminouse seeds for 30mins to remove tannins.

Heating and cooking

It moist heat treatment, the sample is either boiled for 30min at100 C, pressure-cooked for 10min at 120 C, or steamed for 30 min.

In dry heat treatment, the sample is either sun-dried for 6-12 h,oven-dried for 12 h at 60 C, or roasted for 2-5 min at 250 C.

Moist heat is more effective than the dry heat for legume seeds.Cooking improves the digestibility and nutritional value of grains. Heatdestroys the trypsin inhibitor in soybean meal. Heat is also used toextract oil from oilseeds. Dry heat treatment facilitates handling and

pelleting and increases the nutritional value of feedstuff. But boiling,cooking steaming and autoclaving can lower the nutritional value ifprocessing conditions such as temperature, pressure and time are notoptimum.

Extraction with organic solvent

Different organic solvent are used to remove the non-nutritivecomponents of various feedstuffs. For example, extraction of lipid fromleguminous seeds with alcohol and water eliminates the beany flavor.

Extraction of oil from cottonseed meal with hexane decreases the toxingossypol.

Chemical treatment

Chemical can reduce if not eliminate the non-nutrive component ofseedstuffs. Treatment of cottonseed meal with phytase ( an enzyme thatacts on phytate ) makes phosphorous and proteins more available andreduces gossypol toxicity. Cottonseed meal can also be treated with ironsalt but this method produces a darker meal unacceptable to the feedindustry.

Dehulling

Dehulling removes most of the tannins (located mostly in the seedcoat or hulls) from colored beans. Dehulling can be done by soaking theseeds in three volumes of water for 4-6 followed by sun drying for 12 h oroven drying at 80C for 12 h and then splitting using an ordinary cornmill. Another way is by soaking the seeds in the water for 12-48 h andallowing them to germinate. The germinated seeds are then dehulled and

sundried.


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Feed Preparation (Pellet Form)

Feeds for fishes and shrimps must be designed to meet therequirements of each species. Feeds must be:

attractive and nutritious of suitable particle size and texture

of uniform length

free of cracks or fines

stable in water for a few hours (at least 6 h in the case of shrimpfeeds)

durable enough to withstand handling

To achieve these characteristics, feed preparation must follow

stringent procedures.

Grinding

Ingredients are ground to increase the surface area. Grindingimproves mixing, digestibility, palatability and water stability offeedstuffs. The grinding equipment varies with the nature and texture ofmaterials with the desired particle size.

Sieving

Ground feedstuffs are sieved to obtain the desired particle size. Asieve of no. 40 mesh size (425 um) is usually used.

Weighing

The feed components must be weighed as possible. A good andaccurate balance with taring device is best as it can be adjusted to zeroand allows weighing with container.

Mixing

Feed components are sequentially added a little at a time or bybatch. There are two mixing operations, namely: premixing ofmicronutrients and blending of the diet components.

Pelleting and extrusion

Pelleting transforms the soft feed mixture into hard pellets byforcing it through holes in a metal die plate and cutting the noodles downto desired sizes. Pellets before they sink to the bottom of the pond ortank.


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Steaming

Steaming improves the water stability and digestibility of the feedand kills most harmful bacteria. Steamed pellets are stable in water for4-12 h depending on binder efficiency. Unsteamed pellet break up within

30 min. shrimps are slow eaters, so pellets for them must be steamed.

Drying and cooling

Pellets are hot and moist after steaming and can not be handledand stored as they easily break up. Steamed pellets have to be oven-driedat 60C. a draft oven with recirculating warm air allows equaldistribution of heat. Slow and insufficient drying encourages the growthof molds. The pellets must be cooled before storage.

Packaging and storage

Feeds usually have a limited shelf life, which can be shortenedfurther if wrong packing material is used. Pellets are packed and storedin covered plastic buckets and jars or in bags usually in 5, 10 or 25kgamounts. Essential components of feeds may be adversely affected byprolonged exposure to strong light, excessive moisture, poor ventilation,or high temperature.

Factors Affecting Nutrients Stability in Feeds During Storage

1. Moisture content of the feed. Moisture content of more than 10%encourages fungal growth and insect infestation.

2. Relative Humidity. Relative humidity of more than 65% promotesfungal growth and insect infestation.

3. Temperature. High temperature destroys or reduces the availabilityof nutrients.

4. Oxygen supply. Oxygen promotes oxidative rancidity and growth offungi and insects.

5. Lipid peroxidation. Lipids in feeds and feedstuffs can formperoxides that cause rancidity and off flavors. Peroxides may bindwith proteins or vitamins and reduces their availability.

6. Insect infestation. Insect grows best at 26-37 C. They consumethe feed and introduce bacteria through their feces.

7. Fungal proliferation. Fungi grow best at relative humidity >65%and moisture content >10% and temperature that are specific to

fungal species. Fungi damage the feeds, cause weight loss,discoloration and rancidity and produce mycotoxins such asaflatoxin.


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8. Bacterial contamination Salmonella destroys proteins and lipidsand releases toxin. Proper storage sanitation is necessary to avoidcontamination.

Proper Storage Practices

1. For dry feeds and ingredients

Provide a clean, dry, secure and well ventilated storage area.Avoid direct exposure to sunlight.

Label feed and feed ingredients properly. Arrange feeds by kindand date.

Pile feed bags not more than a bag high on a platform 12-15 cmof the floor.

Store dry feeds not longer than 3 months. Use old feeds beforethe new deliveries. First in, first out.

Do not walk on the sacks of feed.

2. For moist or wet feed ingredients

Use fresh trash fishes immediately to keep them frozen untiluse. Use moist compounded feeds fresh.

Keep oils and fats in sealed amber or dark colored containersinside the cold store or refrigerator. Maintain the temperature ofthe cold store below 10C. Avoid overloading and unnecessaryopening of the cold storage.

Ensuring the high quality of feeds

1. During acquisition of feeds

Obtain raw ingredients or prepared feeds from reputablesources. Choose bags that are clean intact, and with properlabel.

Obtain feeds for up to two weeks supply. Prepared feeds aregood only up to 2 months from the date of production.

2. Feed evaluationpractical methods Sensory evaluation (smell and taste)

Spoiled feeds have characteristic smell stale and musty orputrid; taste bitter or sour.

Reliable brands of commercial feeds

B-MegSan Miguel

URCUniversal Robina Corp.

Julu feeds

Vitarich


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Forms of Feeds

1. Mash or Powder form. It is made up of tiny particles of feedsusually less than 1 mm in size. Fry and small fingerlings are givenwith this form of feeds.

2. Crumble. This is also given to younger/smaller fish and usuallycontain higher amount of protein.

3. Pellets. These are compacted mash or powder feeds formed intolarge particles. This form of feed is usually given as soon as theamount of the fish is big enough to swallow the smallest size ofpellets. These pellets can be given in moist form.

4. Dough form or ball form. This is prepared by adding water to the

feed while mixing sticky mash is formed. In the absence of pelletingmachine, feed maybe prepared in this manner.

Mash or powderform Floating pellets Dough form Crumbles

Figure 1. Forms of feeds

Computation of Daily Feed Allowance

Formula:Daily Feed Allowance = W x N x S x R

Where: W (g) = average body weight of the stock after a given period.N = the original number of stocked

S (%) = estimated survival during a given periodR (%) = Feeding rate

Example:

Given: No. of stock in a 1 ha. Pond = 50,000Weight after 30 days = 5 gEstimated survival = 90%Feeding rate = 8%

Daily Feed Allowance (DFA) = W x N x S x R= 5g x 50,000 x 0.90 x .08/day= 18,000 g/day or 18 kg/day


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Total Feed requirement for 15 days = 18 kg/day x 15 days= 270 kg for 15 days

Note: To get the average individual weight of fish, perform/do samplingby weighing the stock individually or in bulk divided by the number of

fish sampled.

Feeding rates

Feeding rate is the basis for determining the amount of feed to begiven to the fish and usually expressed in percentage fish biomass.Recommended Feeding Rates:

Fry 5020%

055 g 2010%550 g 107%50500 g 75%500 g and above 53%

Feeding rate is lowered as the fish grow bigger because of lowermetabolic rate.

Methods of Feeding

1. Hand Feeding.This is the most

economical and practical way offeeding fish. It is the mostapplicable in developingcountries where labor isconsidered cheap. Theadvantage of hand feeding isthat the farmer can observe thefeeding behavior and demandsof the fish.

Figure 2. Hand feeding method

2. Automatic Feeders. Thismethod is applicable in largeponds where large quantities offeeds have to be given in ashort period. Automatic feedersallow better distribution of feedat regular intervals.

Figure 3. Automatic feeder


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3. Demand Feeders or Self-Feeder. Using this method, fishcan obtain food on demandgenerally by dressing a trigger.The advantage of this method is

that the fish can obtain asmuch food as they require asoften as they want. Figure 4. Demand feeders

Feeds can also be placed in other feeding devices such as feedingrings and feeding trays. Feeding trays are usually placed at the bottom ofthe pond to prevent the feed from being buried and can also be served tocheck if the feeds are eaten by the fish. Feeding rings on the other handare placed at the surface to prevent scattering of feeds all over the pondand likewise allow the feeds to sink gradually.

Feeding Tips

Feed the fish not the pond.

Feeding frequency should be modified according to the size of fishand natural food productivity.

Increase feeding rate when natural food production is low.

Adjust feed size with the size of the fish. Use bigger feeds as fishgrow.

Broadcast the feed over a wide area. It allows for more fish to avail

of given feed minimizing size variation in fish population and feedwastage.

Steps in Changing Pond Water

1. Check pH, salinity, dissolved oxygen, water temperature, andtransparency. Any deficiency arising from these parameters couldbe a factor for changing water periodically. This could be as oftenas once every two days. For tide-controlled pond, water should bechange as frequent as the water could enter into the pond.

2. Remove soil seal. If the gate is soil sealed, remove the soil by usingdigging blade or shovel.

3. Detach flush boards from top to bottom. In some instances,especially during rainy season, surface water needs to be removed.To do this, detach only two or three flush boards enough to drainsurface water.

4. Flood in tidal water into the pond. Watch the incoming waterbrought by high tide and be sure to control water flow. Rememberthat excessive water flow will cause strong current that mightdestroy nylon screen or bamboo slats. The installation of nylon


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screen prevents the entrance of wild species and debris into thepond.

5. Close and soil seal the gate. Upon completion of water change, thegate should be soil sealed to minimize leakages.

LET US REMEMBER

Fertilization is important to sustain the growth of natural food inthe fish pond.

Frequent feeding is recommended when the fish are small, naturalfood is inadequate and when the feeds are less stable.

The maintenance of good water quality is essential for positiveresults in rearing fish.


Now that you have finished the lesson, lets find out how much youhave learned by answering the post-test. Answer this in your testnotebook.

Post Test

Write T on the blank if the statement is correct. If false, write F,then underline the word/words that makes the statement wrong thenchange to make it correct.

1. Storage condition should be optimal to avoid deterioration of feedingredients.

2. Relative humidity of less than 65% promotes fungal growth andinsect infestation.

3. Low temperature destroys or reduces the availability of feednutrients.

4. Biomass is the total weight of fish per unit area at a particular time.

5. Frequent feeding is recommended when fish are small and whennatural food is inadequate.

6. Good water quality enhances fish growth and minimizes mortality.

7. Low tide is the ideal time of changing pond water.

8. Soil sealing the pond gate prevents leakages.

9. Proper storage sanitation is not necessary.

10. Increase feeding rate when natural food production is high.


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Store feeds in a well-ventilated, clean and dry area.

Observe proper sanitation inside the storage room.

Compute daily feed ration based on actual sampling of fish.

Demonstrate feeding methods. Observe and demonstrate changing of water in the pond.

RESOURCES

ToolsWater parameter kitWeighing scale or balance

MaterialsFertilizerFormulated feeds

REFERENCES

Operate Fish Nursery Module. Junior Agriculture Technician.Cagauan, A. G. Tilapia Grow Out System and OperatonToledo, C. F. Aquaculture Manual. Pangasinan State University.


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LESSON 4.

PERFORMING AWARENESS ON MONITORING

DISEASE AND IMPLEMENTING TREATMENT


The lesson deals with water management standard monitoringprocedures, procedure in observing, preventing, safeguarding disease andparasite occurrence and ways of determining appropriate treatment.



1. monitor symptoms of disease manifested periodically.2. observe and apply prevention of disease and parasite occurrence

based on accepted practices.3. determine appropriate treatment of disease per species cultured

fish.4. internalize the value of disease prevention and treatment.


Before going through this lesson, try to answer this pre-test. Thiswill enable you to find out what you already know and what you stillneed to know about Performing Awareness on Monitoring Diseasesand Implementing Treatment. Answer this in your test notebook.

Pre-Test

Identify the following by choosing the correct answer from thechoices below:

1. Immersion in a static chemical treatment for a period of time greaterthan 5 minutes.

2. A short bath of less than 5 minutes is known as _______.

3. One dose of chemical is added to inflowing water.

4. Use of external treatment would be the most common method inaquaculture.

5. The drugs to be used are added to the fish feeds.


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6. A constant volume of chemical is added to the inflow water over a fixedperiod of time to give a constant concentration in the pond.

7. This method applies high concentration of chemical to individual fish

without exposing the gills to the chemical.

8. It is not often used, but could be useful in fry or small aquarium fish.

9. It is used for giving antibacterial agents, hormones or vaccines.

10. _________ are bath of no time limits.

a. Immersion f. Injectionb. Bath g. Systemic treatment

c. Dip h. Combination of immersion and systemictreatmentd. Flush i. Permanent bathe. Swabbing j. Flow

LET US STUDY

A fish natural environment is water. When fishes are removed fromwater they are subjected to stress. Low oxygen, pollution, sudden pH ortemperature changes also cause stress to fish. Fishery workers try to

handle fishes properly so that the least possible stress occurs. Properhandling of fish must be observed so that least possible stress will occur.

Fishes that have undergone stress are more likely to have disease.In some cases, as in large volume of water, it is not economical to treatthe fish for disease. Seedling transfer is a situation that will allow foreasy and economical disease treatment. All seedling should betransferred in combiotic solution of 15 parts per million. If loses is stilloccur, one or more other treatments should be tried.

Let Us Define

Bacteriasingle-celled organisms which are small (0.3 to 0.5 micros)and found everywhere in nature.

Virusesthe smallest microorganisms. They range in sizes from 25 nmto approximately 300 nm. They can be visualized only through anelectronic microscope.

Diseasea particular destructive process in the body with a specificcause and characteristic symptoms.

Parasitesorganisms that attack or cling to other organism that hasharmful effect on the attacked organisms.

Diagnoseto identify diseases by examination.


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Early Signs of Diseases

1. Sluggish behavior. The fishes may become very inactive and oftencease feeding. Some lies listlessly on the bottom of the tank while

other just float below the surface of the water.

2. Twirling, spiral or erratic movement. This is indicative neurologicaldamage.

3. Faded pigment. Attributed to the reduction of melanin content.

4. Darkened pigment. An enhancement of pigment results frominfection.

5.

Exophthalmia (pop-eye). The presence of bulging eyes occurs withinfections.

6. Hemorrhage in the eyes. This is characterized by the presence ofblood spots in the eyes.

7. Hemorrhage in the mouth. Blood spot becomes apparent in the roofof the mouth.

8. Erosion of the jaws/mouth. Occurs with infection by Flexibactermaritimus.

9. Hemorrhage in the opercula region by Pseudomonasanguilliseptica.

10.Gill damages. This includes the presence of swollen gill lamellae,clubbing and gill diseases.

11.White nodules on the gills. Characteristics of infection byEdwardsiella tarda.

12.Fin rot. Presence of badly damage (rotted) firms may be a sign ofinfection by Aeromonas hydrophila.

13.Hemorrhage at the base of the fins.

14.Protruded anus/vent.

15.Hemorrhage on the vent.


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General Causes of Fish Diseases

1. Nutritional disordernutritional deficiency syndrome.

2. Environmental factor (e.i. temperature, salinity, oxygenavailability, light and pollutants). These influence disease agentaffects the hostsresponses in numerous ways.

3. Co-existing organisms act as causative agents of disease. Theknown major agent to cause disease includes virus, bacteria,protozoan, fungi, trematodes, cestodes, anthropods,acanthorcephalans.

Figure 1. Relationship among fishes, parasites and environment

4. Geneticsthese are diseases presumed to be genetics in origin.

5. Stress factorstress can be arbitrary divided into -a. Chemical stresses. These include low oxygen levels, high carbon

dioxide, ammonia, and nitrite lead, sub lethal levels ofinsecticides and heavy metals.

b. Environmental stresses. These include extremes in

temperatures and excessive sunlight.c. Biological stresses. These include infestation with external or

internal parasites or a lack of balance diet.

6. Physical injuries. Include stab, bite and scrape lesions, usuallyresult from attack by a predator in the wild. These are usuallycured by graduation unless there is secondary infection.

Treatment Methods

A. Immersion. This method is used for external treatment and would bethe most common method used in aquaculture.

Parasite

Environment

Disease

Fish


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Bath. Immersion in a static chemical treatment for a period of timegreater than 5 minutes. Permanent (or continuous) baths of notime limit. The chemicals are left in the water to be degraded ordiluted out naturally. This is the most common method oftreatment in excessive pond culture.

Disadvantages:a. Because of the static water, the fish may become stressed with a

poor environment.b. Some labour input is needed.c. In ponds, the concentration of the chemicals vary unless it has

been mixed well.

Dip. A dip is a short bath of less than 5 minutes. The chemicalconcentration uses are much higher.

Disadvantages:a. It is very labour intensive.b. It can be harmful to the gills because of high concentrations of

chemical used.

Flush. One dose of chemical is added to the inflowing water. Thechemical is then carried through the pond and diluted by the waterflow.

Disadvantages:

a.The concentration of the chemical is not even throughout thepond.

b. Large amount of chemicals are needed if compared to bathand dip methods.

Advantages:a. It is easyb. It has low labor input

Flow. A constant volume of chemical is added to the inflow waterover a fixed period of time to give a constant concentration in the

pond/tank/raceway.

Disadvantages:a.There must be quite a good glow rate of water.b. High chemical costs because more chemicals are needed.c.The dimension of the pond/tank raceway and the flow rate

need to be known accurately.d. An accurate delivery system is needed.

Advantages:a. An accurate dose can be calculated.

b. It is safe, no stress on the fish.c. It has low labour input.


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B. Systemic Treatment. This method is used in systemic bacterialdiseases and for gut parasite infection. The drug to be used is addedto the fish feeds.

Disadvantages:

a. Some production system does not eat artificial diet and so theywill not eat medicated food.

b. Fish with disease do not eat much so they will not receive thecorrect dose of the drugs.

c. Some drugs are not stable in wet or moist diet.

Advantages:a. It is cheapb. It has low labor input.

C. Combination of Immersion and Systematic Method. This is not usedoften, but could be useful in fry of small aquarium fishes.

D. Swabbing. This method applies high concentration of chemicals toindividual fish without exposing gills to the chemicals. Small amountof chemicals is used. Anesthetics may need to be used so thechemicals can be applied. This method is labor intensive.

E. Injection. This is used for giving antibacterial agents, hormones orvaccines.

Diagnosis of Fish Diseases

A. Surveillance of diseases.

Signs of diseases loss of appetite, abnormal changes in color,physical deformities, abnormal behavior, retarded growth, lethargy,erosion of skin, fin rot and mortalities.

Pattern of mortalitiesa. Sudden, mass mortalities associated with acute

environmental problems.b. Gradual mortalities this may be due to infections disease

agents or nutritional disorders.

B. Basic Procedures in Diagnosis of Diseases1. Recognize early or consistent signs of diseases.2. Check and record water condition.3. Note nature of stock and monitor stock regularly.4. Evaluate sanitation and management practices.5. Perform diagnostic test.

Basic Management Approaches to the Prevention and Control ofDiseases

1. Stock healthy fish. Use disease-free fish, egg, or fry for stocking. Allnew fish introduced of the farm should not be mixed with the fish


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already on the farm straight away. Quarantine of the newlypurchased fish is a good practice especially if the disease status ofthe fish is not known.

2. Monitor fish health. Fishes should be checked daily by noting

feeding activity and general behavior.

3. Control wild fishes, vectors, pests and other animals in cultureponds. Wild fishes and other animals act as intermediate host forfish parasites. They are also the greatest source of disease-producing organisms. They should be - screened out. poisoned especially during pond preparation. shot or scared away especially the birds, nests and trees

near the ponds should be removed to prevent fecal

contamination of the water.

4. Sanitation and hygiene. Avoid the build-up of faces, detritus,uneaten food and dead fish. At least once a year or preferably afterevery production cycle, ponds should be drained.

5. Population regulation and stock age grouping. Overstocking shouldbe avoided at all times. In situations where overstocking hasoccurred competition between the individual fish increases andstress will result. High stocking levels also facilitates parasitesspread. Overstocking may affect water quality resulting in

increased B O D, (biological oxygen demand), reduced D O(dissolved oxygen), increases in ammonia nitrogen and increasedbacterial counts.

6. Immunization (or vaccination). This techniques has not becomecommonly used in fishes as it has done in other animals and man.

7. Use of disease-resistant strains of fish. Resistance to disease canbe selected in any population over a period of time, species thathave been cultured for a great number of years, usually naturallyselect themselves so that the population becomes more adapted tothe artificial environment. This results to fishes that are lesssusceptible to stress and thus less likely to overcome diseases.

8. Avoidance of stress. This is the most important way to avoiddiseases. Do not overstock. Maintain water quality parameters within the suggested

guidelines. Maintain water flow. Recognize the climatic changes and other stressors (e.g.

handling, transport). Provide a fresh well-balanced diet in sufficient quantities.


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LET US REMEMBER

Poor fish health are due to slow growth, poor feeding, low yields,increased disease incidence and mortality and low profitability.

Handle fishes with special care when collecting, holding,

transporting, stocking and sampling to avoid stress, diseases andpossibly death of fish stock.


Now that you have finished the lesson, lets find out how much youhave learned from it by the answering the post- test. Answer this in yourtest notebook.

Post Test

Identify the following by choosing the correct answer from thechoices below:

1. This method applies high concentration of chemical to individual fishwithout exposing the gills to the chemical.

2. One dose of chemical is added to inflowing water.

3. Immersion in a static chemical treatment for a period of time greaterthan 5 minutes.

4. It is used for giving antibacterial agents, hormones or vaccines.

5. It is not often used, but could be useful in fry or small aquarium fish.

6. The drugs to be used are added to the fish feeds.

7. A constant volume of chemical is added to the inflow water over a fixedperiod of time to give a constant concentration in the pond.

8. __________ are bath of no time limits.

9. A short bath of less than 5 minutes is known as _________.

10. Use of external treatment would be the most common method inaquaculture.

a. Immersion f. Injectionb. Bath g. Systemic treatmentc. Dip h. Combination of immersion and systemic

treatment

d. Flush i. Permanent bathe. Swabbing j. Flow


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1. Demonstrate method of treatment.2. Follow basic procedures in the diagnosis of diseases

3. Identify signs and symptoms of diseases.4. Demonstrate proper procedures in monitoring and observing

diseases.5. Observe personal safety.

RESOURCES

ToolMicroscope

MaterialsSlideSample fish disease

REFERENCES

Operate Fish Nursery Module. Junior Aquaculture Technician

Sarmiento Jr., Regino S. Module in Fishpond Engineering andManagement.


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LESSON 5.

HARVESTING AND ADOPT PROPERPOST-HARVEST HANDLING


The lesson deals with scheduling tips for timely harvest, ways onpreparing supplies and materials required in harvesting operation,procedures in observing, capturing, hauling and handling fish duringharvest, and proper ways on conditioning, grading, counting, packing livefish handling, transporting and marketing.



1. observe proper schedule in harvesting.2. prepare supplies and materials required in the harvest operation

according to standing crop.3. observe capture and handling procedure based on accepted

standards to maintain good quality of fish fingerlings duringharvest.

4. observe proper ways of conditioning, grading, counting, packing,live fish handling and transporting fish.


Before you go through this lesson, try to answer this pre-test. Thiswill enable to find out what you already know and what you still needknow about Harvesting and Adopt Proper Post-Harvest Handling.Answer this in your test notebook.

Pre-Test

A. Write TRUEif the statement is correct and FALSEif incorrect.

1. Transporting fish alive by packing in polyethylene bags employclinical/medical oxygen in order to keep them alive.

2. Excessive stress is harmless to fish.3. The fry or fingerlings are not fed for at least two hours prior to

transport.4. Percentage method of counting fingerlings can be obtained by

comparing the density of fish in a container to the other container.5. Oxygen is essential in packing fish in polyethylene bag.


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B. Choose the letter of the correct answer.

6. The advantages of preparing harvesting supplies and materials are thefollowing except -a. makes harvesting difficult

b. provides spontaneous and systematic movementc. lessens time and effortd. hastens work flow and activities

7. Another name for current method of harvesting is -a. seining methodb. draining method

c. freshening methodd. none of the above

8. One of the causes of mortality during transporta. similar salinity and temperature of water inside the container

b. oxygen depletion due to leakage of plastic bags, delays in transport,decomposition of debris, high bacterial count of transport waterc. maintaining low temperature during transportd. acclimatization of stocks before transport

9. To reduce mortality during transport, you should able to -a. transport only healthy fishb. allow the fry to recover from handling stressc. acclimate the fry to lower salinity before transportd. all of the above

10. A method of counting fingerlings that are counting individuallya. visual estimationb. direct method

c. percentage methodd. all of these

LET US STUDY

In about 4-6 weeks of rearing, the fish grow to 5-8 cm in totallength (fingerling size) which is ideal size for releasing in grow-out pondsor pens.

Excessive stress is harmful to fish. The use of stress-free gear incollecting seedlings in the pond is ideally necessary. However, there is noexisting gear of this type. Practically, one should only explore thepossibility of availing a gear and technique of catching fingerlings atminimal stress.


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Let Us Define

Harvestingthe process of collecting or gathering of fish stocks.Fish Gradingthe process of separating desired size of fish from small

one (when different sizes are mixed).Mortalitythe death rate of fish per culture period.Depletionthe loss or lacking of one thing.Transportto carry from one place to another.Temperaturethe degree of hotness and coldness of water.Salinitythe total amount of concentrated salt in the water.pptequal to mg/L.

Harvesting Materials

Advantages derived from preparation of harvesting supplies andmaterials are as follows:

1. It facilitates easy harvesting.2. It lessens time to be consumed.3. It lessens effort to be spent.4. It provides spontaneous and systematic movement.5. It hastens work flow and activities.

Supplies and Materials for Harvest Operation

1. Scoop netis used for scooping fish in the water.2. Polyethylene bagis used for packing and transporting fry and

fingerlings.3. Rubber bandis used in tying after filing in the bag with oxygen.4. Water pailis used in pitching water.5. Plastic basinis used for counting fry6. Bowlis used for counting fry.

Figure 1. Scoop net Figure 2. Polyethylenebag with fish

Figure 3. Rubber band


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Figure 4. Water pail Figure 5. Plastic basin Figure 6. Bowl

Methods of Harvesting

1. Freshening or Current method. The fishes have the tendency to swimagainst the current. This tendency will harness in catching them.

2. Draining method.The pond should be drained totally during low tide atnight time. When the fishes are confined in the pond they are easily

scooped. This method enables one to remove all undesirable fishes inthe pond.

3. Seining method.This method is used if partial harvest of the stock isrequired.

Steps in Collecting Fingerlings in the Nursery Pond

1. Drain about 50% of pond water. It is necessary to decrease water inthe pond so that the fish may easily detect the presence of incoming

water. The reaction of fingerlings to the incoming water should beobserved. If necessary leave only a small amount of water in the pondto enhance positive fish reaction to water current.

2. Install fingerling seine at the catching pond, preferably near the gate.Fingerling seine is featured like an inverted mosquito net.

3. Lift the net. This means that only a portion of the net is being liftedand the remaining part is submerged underwater. The net is broughtclose to the dike, and the fingerlings are ready for counting.

4. Repeat steps 2 and 3 until there are still fingerlings reacting to watercurrent.

5. Drain the pond up to 30 cm. The reduction of pond water facilitatesthe seining of the remaining fingerlings in the pond.

6. Catch the remaining fingerlings with the use of seine net. It isadvisable to maintain a certain quantity of water to make sure thatthe fingerlings are still alive. Seine net should be operated slowly toprevent too much stress on the fish.


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7. Place in a plastic basin, aerate if possible.

8. Bring the fingerlings to the rearing pond.

Methods of Grading Fry and Fingerlings

This is achieved by using the following:

A. Fish Grading Panel filters/screens the desired size of fish. The netwith desired size is fixed at a wooden frame whose width is equal tothe width of the tank.Steps:

1. Concentrate the fry in one side of thetank by creating some motion in the

water.

2. Install the panel to fit the width of tank.

3. Move the panel slowly towards theconcentrated fish. It will be observed that the smaller ones passout through the mesh while the bigger ones retains on the otherside.

4. Scoop the desired fishes.

Figure 8. Concentratingthe fry in one side of the

tank

Figure 9. Installing thepanel

Figure 10. Moving thepanel slowly towards the

concentrated fish

B. Floating Grading Box a net formed like abox. The mesh size is enough tograde/separate the desired fishes.Steps:1. Place the box inside the tank. Be sure the

box is not totally submerged in water.2. Place the fry inside the grading box. Those

that are smaller pass out and those thatare retained will be transferred to anotherholding unit.

Note: Always observe safety measures to minimize stress and mortality.

Clean and clear area after work.

Figure 7. Fish GradingPanel

Figure 12. Floatinggrading box


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Methods of Counting Fingerlings

1. Direct method. Fry are counted individually. For large number of fryin one cup or bowl, or any convenient multiple is represented by acorresponding number of pebbles, shells or stones to aid in

counting. For instance, one pebble may represent 100 fingerlingswhile bigger one would represent 1000 fingerlings.

2. Visual estimation or subay system. This method is used by fryconcessionaires and dealers. The density of fry in one container iscompared with that of the other container for which the exactnumber of fry has been previously determined.

3. Percentage method.The buyer arranges with the seller to stock allfry bags equally. He then selects the bags at random. The total

number of fry can be obtained by multiplying the average numberof fish per bag by the total number of bags.

Steps in Preparing Packing Materials and Equipment

Figure 13. Leaning andtying of oxygen tank

Figure 14. Fitting aplastic tube or hoseinto the tank valve.

Figure 15. Opening thegas regulator grades

gradually

1. Bring all the necessary tools, equipment and materials near theplace of harvesting the fingerlings.

2.Lean and tie the oxygen tank with a rope on the post or stand erectto prevent it from falling own or simply lay down the tank on thefloor putting pieces of wood or stone on both sides just enough tokeep it from moving or rolling.

Note: If you cannot carry the tank by yourself, seek for help fromother person/s or classmate/s.

3. Get the plastic tubing or hose and fit it tightly into the tank valvewhere oxygen passes through. Fasten with rubber band to preventleakage.

4. Operate by opening the gas regulator gradually to test whetherfitting is tight and to determine if leakage is present or not.


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Notes:a. A whizzing sound is produced at the fitting if ever there is

leakage. Air (oxygen) escapes through it.b. If it happens, dismantle the fitting and reassemble it

c. Rest it again

5. Check scoop net and screen/filter. Be sure these are damage freeand not worn out.

6. Wash basin with clean water. These should be of the same size andcolor. The number of basin depends on the number of fingerlings tobe harvested. You must have an estimate of the number offingerlings to be harvested.

7.

Fill the polyethylene bag with clean water about of its watervolume.

Note: Never use damage polyethylene bags, they do not store wateror trap oxygen.

TRANSPORT OF FRY AND FINGERLINGS

General Practice

The fry or fingerlings are not fed for at least two hours prior totransport. They are placed in containers with clean water of similarsalinity and temperature. They are then counted usually by visualestimation in small lots. Water temperature is maintained at 26-30 C ifthe number and/or size of fry is small and transport time does notexceed 6 hours. At higher stocking densities, bigger fry sizes and longertransport times, temperature is reduced to 20-22 C. Lowering of thewater temperature is done by placing in the transport medium a smallplastic bag of ice (use of bags prevent reduction in salinity). Care shouldbe taken that the temperature does not drop below 20 C. The desirednumbers of fry are poured into double plastic bags. Oxygen is introducedat a volume equal to or twice that of the water in the bag. The plasticbags are then placed inside pandan bags in case of land transport. Icedwrapped in newspaper may also be placed on top of the plastic bags of fryto maintain low temperature during transport.


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Figure 16. Fry to be transported are placed in double plastic bags, to whichoxygen is added. These bags are placed in pandan bags for short distancetransport, or in Styrofoam boxes and cardboard boxes for long distance transport.Small bags of ice are placed in transport containers to maintain low temperature.

Causes of Mortality during transport

1. Physical injuries2. Overcrowding due to high number or large size of fishes

transported.3. Oxygen depletion due to leakage of plastic bags, delays in

transport, decomposition of debris, high bacterial count oftransport water.

4.Thermal stress due to high (30C) or low (20C) temperature.5. Accumulation of toxic waste products like ammonia in the water.

Ways to reduce mortality during transport

1. Acclimatize the fry to lower salinity before transport. The salinityshould not be more than 5 ppt difference from that of the storageor pond salinity at the destination.

2. Do not feed the fry for at least two hours before transport.

3.Transport only healthy fry.


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4. Allow the fry to recover from handling stress for at least 12 hoursbefore transport. This would increase their resistance tosubsequent stress.

5. When water temperature has to be lowered, it should be done

gradually, approximately 1C per minute and should not go lowerthan 20C.

6. Avoid unnecessary handling and transfer of fry. Follow the capacityof any transport receptacle used.

LET US REMEMBER

Preparing harvesting materials, tools and equipment is one major

activity to be performed before harvesting is undertaken. Do not feed the fry for at least 2 hours before transport to avoid

mortality


Now that you have finished the lesson, lets find out how much youhave learned from it by answering the post-test. Answer this in your testnotebook.

Post Test

A. Write TRUEif the statement is correct and FALSEif incorrect.

1. Transporting fishes alive by packing in polyethylene bags employclinical/medical oxygen in order to keep them alive.

2. Excessive stress is harmless to fishes.

3. The fry or fingerlings are not fed for at least two hours prior to

transport.

4. Percentage method of counting fingerlings can be obtained bycomparing the density of fishes in a container to the othercontainer.

5. Oxygen is essential in packing fishes in polyethylene bag.


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B. Choose the letter of the correct answer.

6. The advantages of preparing harvesting supplies and materials arethe following except -a. makes harvesting difficult

b. provides spontaneous and systematic movementc. lessens time and effortd. hastens work flow and activities

7. Another name for current method of harvesting is -a. seining methodb. draining method

c. freshening methodd. none of the above

8. One of the causes of mortality during transport is -a. similar salinity and temperature of water inside the container

b. oxygen depletion due to leakage of plastic bags, delays intransport, decomposition of debris, high bacterial count oftransport water

c. maintaining low temperature during transportd. acclimatization of stocks before transport

9. To reduce mortality during transport, you should have to -a. transport only healthy fishesb. allow the fry to recover from handling stressc. acclimate the fry to lower salinity before transportd. all of the above

10. A method of counting fingerlings that are counting individually -a. visual estimationb. direct method

c. percentage methodd. all of these


a. Identify and prepare harvesting supplies and materials.b. Count fishes using different methods of counting.c. Grade fishes using grading panel or floating grading box.d. Lean oxygen tank on the post to stand erect.e.Tie tank on post to stand erect.f. Fit plastic tubing/hose tightly into valve.g. Fasten fitting with rubber band.h. Open gas regulator gradually.i. Check leakage by observing whizzing sound.j. Check scoop net/screen for damage.k. Check polyethylene bag for damages thoroughly.


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RESOURCES

ToolsSeine net (fine net)Aerator

Oxygen tank

MaterialsBasinPolyethylene bag

REFERENCES

Villaluz, A. C. et.al. 1983. Milkfish Fry and Fingerling Industry of the

Philippines: Methods and Practices. Aquaculture SEAFDEC

Bagarinao, T. U. et.al. 1986. Important Fish and Shrimp Fry in thePhilippine Coastal Waters: Identification, Collection and Handling.Aquaculture SEAFDEC


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ANSWER KEY

Lesson 1

Pre-test:1. c2. c3. d4. b5. d6. a7. c8. c9. b

10. a

Post-test:1. c2. c3. d4. b5. d6. a7. c8. c9. b

10. a

Lesson 2

Pre-test Post-test1. T 1. T2. T 2. T3. F 3. F, change 1,000 to 10,0004. F 4. F, omit not5. T 5. T6. T 6. T7. T 7. T8. F 8. F, omit not9. F 9. F, change feeding to stocking

10. F 10. F, omit not

Lesson 3

Pre-test Post-test1. T 1. T2. F 2. F, change less to more3. F 3. F, change low to high4. T 4. T5. T 5. T6. T 6. T

7. F 7. F, change low to high8. T 8. T9. F 9. F, omit the word not10. F 10. F, cha

fish culture y4

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