A seminar on

Breeding of Coldwater fishes

(trouts and mahseers)

Faq-317

.

contents Introduction

Coldwater fishes (trout)

Breeding of trout

1. Natural breeding

2. Induced breeding

Coldwater fishes(mahseer)

Breeding of mahseer

1. Natural breeding

2. Induced breeding

Conclusion

References

•Hill areas offer good scope for the development- of fisheries—both for commercial and sport purposes.

•The coldwater fishery resources in India comprise high and mid-altitude lakes, rivers, streams, their tributaries and reservoirs dammed across such rivers.

•The importance of coldwater fisheries lies in their unique biodiversity, valuable germplasm and maintenance of environmental quality in hills.

•Coldwater fishes breed naturally but since some species have been listed as endangered, therefore artificial breeding is now being practiced to restore the diversity.

Coldwater fishes Fishes having the temperature tolerance limit just

like the salmonids i.e. 00 C-200 C are called coldwater fishes. Their optimum temperature range is 100 C-120C.

General modifications:

1) Streamlined bodies.

2) Mouth modified for sucking or burrowing.

3) Narrow gill openings.

In India 258 species of coldwater fishes belonging to 21 family and 76 genera are available.

Coldwater fishes of IndiaFood species Sport species Ornamental species

Indegenous: Tor putitora.

T. tor.

Neolissocheilus spp.

Lepidopygopsis spp.

Osteobrama spp.

Tor putitora.

T. tor

T. khudree

T. malabaricus

Brachydanio rerio

Danio devario

Labeo nandina

Lepidocephalus guntea

Exotic: Cyprinus carpio

Oncorhyncus mykiss

Hypophthalmichthys

molitrix

Ctenopharyngodon

idella

Salmo trutta fario Gageta cenia

Conta conta

Carassius carassius

C. auratus

SYSTEMATIC POSITION OF TROUT

Kingdom: AnimaliaPhylum: ChordataClass: ActinopterygiiOrder: SalmoniformesFamily: SalmonidaeGenus: OncorhynchusSpecies: O. mykiss

Some important trouts

Onchorynchus mykiss (Rainbow trout)

Salmo trutta fario (Brown trout)

Schizothoraicthys richardsonii S. curviforns

Salvelinus fontinalis S.micropogon

SNOW TROUTs

Sexual dimorphism of Trouts

The sexes can be distinguished during the breeding season.

The lower jaw of the males is turned up into a kind of hooked beak shape where as in female it is absent.

A genital papilla is present in the fully ripe female.

Change in body colouration in male. Colourbecoming brighter during breeding season.

FEMALE TROUT

MALE TROUTMALE TROUT

Breeding of trouts Spawning season:

In India trout breeds during December-January, where as rainbow trout breeds during Februaryand March .

Natural breeding ground/ habitat:

All trout return to rivers and streams for spawning. The trout seek out gravel beds(pea sized gravels are best) with good water flow over it to bring in oxygen and carry away silt.

Spawning behaviour:

The hen fish cuts a trench(redd) in the gravel with the tail fin and is then accompanied by the male.

Age at first sexual maturity:

In case of male, milt is best in the age group between 2nd and 4th yr. Female are used for breeding from 3+ years onwards up to 6th yr. Generally Trout attain maturity at the end of 2nd yr.

Fecundity:

The fecundity of trout is very low around 1500-2000 eggs per kg body weight.

• Hundreds of eggs and milt are squirted into the base of the redd simultaneously.• Thus fertilized the eggs absorb water and sink. They are quickly covered up by the female.• Inevitably eggs miss the reddand drift downstream.• Fish including other trout will eat them, but some will find their way into other cracks and crevices where they may well develop.

Natural breeding

Induced breeding

• Pituitary extract @ 2-25 mg/kg in case of female and 2-16 mg/kg in case of male or they are striped directly.

• The fertilized eggs are reared in both stagnant and running water conditions

Hatchery unit

• Brood stock unit 1) Optimum climatic conditions must be

maintained.

2) A proper water source must be available.

3)Water quality must be good.

•Egg taking& milt collection unit:Here egg is collected by stripping by wet or dry

method.

Contd….. Incubation unit:

The incubation devices for trout eggs are:

1) Flow through and Trays

2) Vertical flow incubators

3) Jar incubators

Larval rearing unit:

•Flow through and Trays.

•Vertical flow incubators

•Jar incubators

Females are squeezed for eggs.

Eggs. Milt is collected

from males

Milt

The milt is mixed

with the eggs and a

little saline solution

The mixture is poured

into fresh water. After 1

hour the fertilized eggs

are transferred into

incubator.

Eggs in incubating jar Water is piped into the bottom of the

jars and flows out the top. Jars are

wrapped to keep them dark

Eggs with eye spots.

The white eggs are

dead

Incubating jarsThe fish at this stage are

called Sac Fry

Mahseers

Mahseer, at one time considered to be of single species, is now represented by six valid species distributed all over India.

Despite their abundance, at one time their catches have dwindled considerably by now.

In the effort to conserve mahseer breeding of mahseer, with and without hypophysation has been undertaken.

Kingdom:AnimaliaPhylum: ChordataClass: ActinopterygiiOrder: CypriniformesFamily:CyprinidaeSub family:CyprininaeGenus :TorSpecies: Tor khudree

Tor tor Neolissochilus wynaadensis

Tor putitora Tor khudree

Reproductive biology•SIZE AT FIRST SEXUAL MATURITY:-Males at 1.5-2 yr.

Females at 3yr.

•SEXUAL DIMORPHISM:•Size of the body :

Male are smaller and body narrower than female. Abdomen is bulkier in female. Ventral profile of abdomen is straight in male.

•FinsThe pectoral fin of male is longer than that of female. In male it reach upto

6th lateral line scale. In female it reach upto 5th lateral scale.

•Tubercle on head In male tubercle are present on either side of head which is absent in

female.

•Body colourMales are brighter in colour and black sport on the lateral side of mouth.

Breeding of Mahseer Spawning season:

The breeding season of all mahseer species extends from July to September with a peak in July - August and in exceptional cases to October, and even beyond which has been observed.This has shown the adaptability of the species to different environments.

Natural breeding ground/ habitat:

The breeding habitats usually comprise the marginal lake areas where streams draining the adjoining hills cascade into the lake. The journey to these grounds may be safe or fraught with risks and dangers, but their inner instinct drives the spawners to meet the challenges in order to breed.

Spawning behaviour:

The ripe fish in the lake are attracted by the sound and the incoming well oxygenated running water, and they congregate in the area. If the streams are negotiable, the broodfish migrate into them and cannot be captured.

Physiochemical characteristics for breeding:

Water temperature - 10.50 C-26.50 C

pH- 7.1-7.9

Dissolved Oxygen- 8.2- 11.5 mg/litre.

Fecundity:

Mahseer species have very low fecundity of 10 000 to 15 000 per kg of body weight,

Natural breeding In nature, the spawners try to reach their favoured

spawning grounds which may be in the vicinity or far away.

The hatching period of different mahseer species is in water temperature of 200C- 280C is 92 hrs.

If water temperature falls below 200C, the hatching period extends beyond 96 hours.

induced breeding Healthy broodfish of minimum 3 years is either

collected from nature or cultured in pond.

Fishes are then administered injection of pituitary extract(2 doses) or ovaprim (1 dose) .

Dose:

Female(2 doses)-initial 6mg/kg and final 12mg/kg body weight.

Male-one dose is given @ 6mg/kg body weight.

Ovaprim-Female(0.6-0.8ml/body weight) and Male(0.2-0.3ml/body weight).

Stripping the fishes after 6-12 hours and keeping the fertilized eggs in trays.

The fertilized eggs are demersal, lemon yellow or brownish golden in colour.

Transferring the fertilized eggs in Flow -through hatchery.

Stripping of mahseer

Flow-Through Hatchery Hatchery unit:

A hatchery, for incubation for eggs and rearing of swim up fry, is generally sheltered with a roof having number of hatching troughs and tanks, especially designed for this purpose.

Troughs:(220cmx50cmx40cm or 220cmx60cmx50cm )

Rectangular troughs made of cement, fiberglass etc. are arranged in a series such that water flows into the first trough to subsequent ones. Each trough has separate inlet and outlet mechanism. A trough with five hatching trays can hold 20,000-25,000 fertilized eggs.

Trays:(50cmx30cmx10cm and 3-4 inches in height)

The hatching trays made of fiberglass/wood may be rectangular or square such that 4-5 trays can fit in each troughs. The bottom of each trays is fitted with synthetic netting cloth to ensure regular water movement. Each tray can hold 4,000-5,000 fertilized eggs.

Nursery tanks:

The nursery tanks are another important component of the hatchery, which are used for rearing early fry of mahseer during their initial feeding stage. These tanks can be of many shapes and sizes but depth must be less.

Fry ponds/tanks:

The advanced fry reared in the nursery are transferred to earthen ponds for raising mahseer fingerlings.

Flow-Through Hatchery

conclusion

Coldwater fishes have a huge potential of contributing towards the fisheries sector.

For this reason coldwater fisheries has also been termed as “The Sleeping Giant”.

Coldwater fishes forms both the ornamental and consumable product and hence its protection, enhancement and maintenance is a must.

References

Handbook of Aquaculture-S. Ayyappan

Breeding of Finfish and Shellfish- P.C. Thomas

http://www.fishweb.com/recreation/fishing/fishfacts/fish/rainbow/rainbow.html.

http://www.ets.uidaho.edu/4-h/sportfishing/fish_id_anserws.htm.

http://www.wild-trout.co.uk/rainbow.htm

www.wikipedia.com

www.googlesearch.com

Class notes