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CHAPTER - LI

2. 0. FOOD AND FEEDING HABITS

2.1. INTRODUCTION

Studies on food and feeding of animals are of great importance to

understand growth, migration, reproduction and seasonal variation in body

condition (Suresh Kumar, 1998). Information on natural diet of fish is a necessity

for understanding its nutrient requirements and to know the interactions with

other organisms (Royce, 1989). Moreover, observations on food and feeding

along with the species assemblages structure will help us to understand the

extent of competition for food among different populations. Basic knowledge on

the food preference and feeding of a species is of primary importance to

ascertain its suitability/ compatibility in aquaculture practice in culture systems

with minimum interspecies competition for the natural food (NBFGR - 2000).

11

The application of food and feeding habits of fishes is also one of the ways to

control the waterborne disease (Menon and Checko, 1958). It also provides vital

cues to develop supplementary feed for the species. The food and feeding habits

of some freshwater fishes were studied by Mookrjee (1945, 1944); Kamal (1964);

Das and Moitra, (1963, 1955, 1956, 1958); Bhatnagar and karamenaani, (1970);

Vinci and Suganam (1981); Chacko and Kuriyan (1949); Kurup, (1993);

Annamercy et al., (2001); Mookerjee and Mazumder, (1946); Alikuni, 1956;

Nataraj, 1972; Natarajan and Jhingran (1961); Quasim (1964); Rajan (1965);

Pandian (1966); Singha (1972); David and Rajagopal (1975); Pathak (1975);

Badola and Singh (1980); and Sharma et al., (1988). Even though from early 1980s

onwards scientific community had give much attention in this line, except for

the studies on the biology of some threatened fishes such as the hill stream bach

N. triangularis (Rita kumari and Balakrishanan nair, 1979). Tor putitora (Nautiyial

and Lal, 1982), Labeo dussumieri (Kurup, 1990) more works are needed in these

aspects. An analysis of the food and feeding habits also play an important role in

conservation and management of genetic resources. (Nagi and Tajima, 2002;

Manoj kumar and Madhusoodana Kurup (2002a); Eupherasia and

Madhusoodana Kurup (2002); Bala Krishna and Madhusoodana Kurup (2003);

Manoj kumar and Madhusoodana Kurup (2002b). Geetha et al., (1990) recorded

that Puntius vittatus adopted their life in relation to environmental along with

the food-feeding habitat; Kurup (1993) studied food and feeding habits of

spawn, fry, fingerlings and juveniles of P.vittatus. Mercy et

12

al., (2002) described the food and feeding habits of Punt-ius melanampyx an

endemic ornamental fish of Western Ghats. Basutha and Wisvanath, (1999)

investigated the food composition of various size groups of Otnpok belegari an

endemic carp of Manipur and explained the anatomical feature of the

alimentary canal compatible to the food and feeding habits of the fish.

Regarding food and feeding habits of M.gulio only a limited number of studies

was made by Yusuf and Pulak kumar Majumdar (1993), David (1963), Pandian

(1972). The present study has been attempted to report complete details of food

and feeding habits of M. gulio.

2. 2. Material and Methods

2. 2.0. Description of Test Fish

2.2.1. Systematic positionPhylum: ChordataSub phylum: VertebrataGrade: PiscesSuper class: GnathostomataClass: ActinopterygiiSub class: NeopterygiiDivision: TelosteiOrder: SiluriformsFamily: BagridaeSub family: BagrinaeGenus: MystusSpecies: gulio

Mystus gulio is a semi- aggressive freshwater catfish. In Tamil Nadu it would be

called as "Mangaluru"(p( 1e 2.1)

13

4 5 6 7 8 9 1011, _ 12 .13 14151

17 18

::11

Plate 2.1 - Mystus gulio

Distribution in Asia: Countries bordering the eastern Indian ocean, from India to

Indonesia and Vietnam; reported from Pakistan (Taiwar and Jhingran 1991).

Primarily it prefers brackish water but in freshwater also it occurs mainly in larger

water bodies (river and streams) with mud or clay substratum rarely found in

smaller streams, forms schools of 10 to 25 individuals (Pethiyangoda, 1991).

2. 2. 2. Description of Study Area

River Tambraparani (Map-2.1) originates from Agsthyamalai on the

eastern slopes of Southern Western Ghats at an altitude of 2000m and runs

through Tirunelveli, Tamil Nadu. Sand carried by the river is copper colored,

hence the name Tambaraparani which in Tamil means "bearer of copper" (Rama

devi et al., 1997). Several tributaries like Servalar, Manimuthar, Gadananadhi,

Pachiyar and Chittar join the main river Tambaraparani from a compact drainage

basin. Earlier work on the upper reaches of Tambaraparani River was contributed

by Silas (1953), Johsingh and Vickram (1987) and Rama Devi (1992a, 1992b).

2. 2. 3. Fish Collection

Monthly fifty samples of M. gulio were collected from Tambaraparani river

basin. The specimens were preserved immediately in 5% formalin and brought

back to the laboratory (Centre for Aquaculture Research and Extension, (CARE)),

St. Xavier's college, and Palayamkottai. Length and weight were measured and

the intensity of the feeding was noted based on the state of the distension of the

gut. The point's method as described by Hynes (1980) and Pillay (1952) was

adopted for the gut content analysis. The amount of food contained i.e., as empty14

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(when the gut is almost empty), poor (when the gut contained little amount of

food), moderate (when the gut was half full), good (when the guts was almost

full and gorged). The gut contents were identified up to the species level as far as

possible. Depending on the intensity of the feeding and gut fullness, points were

given to the stomach as 20, 15,10,5 and 0 for full, good, moderate, poor and

empty conditions. The percentage occurrence of different food items was

determined by summing up the total occurrence of all items from which the

percentage occurrence of each food item was calculated (Hynes, 1950). The index

of preponderance was worked out based on Natarajan and Jhingran (1962). The

morphological assessment of food and feeding habits was carried out by

observing the mouth- position, mouth- gap, lips, jaws, teeth, gill rackers,

stomach, vent, intestine etc, in detail for categorizing the fish as one among the

three groups Viz; herbivorous, carnivorous, and omnivorous. The Relative

Length of Gut (RLG) was worked out following the method described by Al -

Hussain (1949) as

Length of the gut (cm)

RLG =

Total length of the body (cm)

2. 3. Results

2. 3. 1. Alimentary Canal and Feeding Habits Morphology

The alimentary canal of M.gulio consists (Fig- 2.1) of buccopharnx,

oesophagous, stomach, intestine and rectum. The rectum however is not

15

ANUS ANUS

MOUTH

INTESTINEINTESTINE

DORSAL VIE

LVIEW

OESOPHAGU

STOMACH

OESOPHAGUS

STOMACH

FIG.2.1. ALIMENTARY CANAL OF Mystus gullo

Table: 2.1 Morphometric assessments of food and feeding habits of M. gulio

distinguishable from out side. The mouth is sub terminal and inferior in

position. The buccal cavities are provided with various minute teeth. The

esophagus is a thick walled tube connecting the buccopharnx with the

stomach. The stomach has the appearance of a 'U' shaped bag having a

cardiac and a pyloric part. Almost the stomach remains covered with the

bilobbed liver. Following the stomach is the intestine, which is wide at the

anterior end and after forming a coil, joins with the rectum. The posterior

end of intestine and the rectal region have almost same diameter. The gut is

short with RLG ranging between 0.64 and 0.73 (AV, 0.67). Morphmetric

assessments of feeding habits of M.gulio are given in Table - 2.1. Most of the

characters of the test fish indicate its omnivorous feeding habits. The special

characteristics such as moderately built jaws, less and moderately long gill

rackers and moderately long and few coils in intestine conforms that M. gulio

is an omnivorous fish.

2. 3. 2. Food compositions

The gut content of M. gulio was found to contain 11 food items

(Table - 2.2). Fish (Puntius spp, Macropodus cupanus), insects larvae (dragonfly,

damselfly, water scorpion and chironomus), crustacean (broken shells of prawns,

naupli, and mysis larvae) were the main food composition of M.gulio . Other

items of algae, copepodes, rotifers, cladocerans, crustaceans, unknown matters

and degraded matters were also recorded. Decayed and unknown matters were

found to be a major portion in all monthly samples.16

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These observations indicated that fish exhibited bottom dwelling habit. The

percentage of each category of food items were described as follows.

2. 3. 2. 1. Algae

Green algae belonging to the family of Chiorophycea,

Spirogyra, Ulothorax, Odogonium and Zygonema were found abundantly in the

food. The percentage of occurrence was found to be 36%-80%.

2.3.2.2. Zooplankton

Zooplankton such as copepods (39%-76%), rotifers (40%-76%) and

cladocera (30%-64%) were observed.

2. 2. 3. Insect Larvae

Some insect's larvae and nymphs (Naiads) Viz., dragonfly, damselfly, water

scorpion, chironomus larvae (36%-78%) were observed.

2. 3. 2. 4. Crustacean

Mainly crustacean appendages, broken shells, and prawn nauplius, mysis and

lucifers (19.2%-68%) and molluscan shells and muscles, which constituted 20%-

66%.

2. 3. 2. 5. Detritus

Decayed forms of vegetative matters were observed as greenish

mass with unshaped appearance.

17

2. 3. 2. 6. Annelid worms

Mainly constituted by earthworms and some unknown items of annelids (22%-

74%) observed.

2. 3. 2. 7. Fish and Fish scales

Puntius species, and fish scales were present at 20%-76% and 8%-70%

respectively.

2.3.2.8. Unknown items

Most of the miscellaneous matters like twigs, shell matter, seeds

and plant matter, semi- digested animal tissues (28%-69.2%) were mainly

present.

2.4. Seasonal variation of food items

The monthly variation of food items was analyzed based on index of

preponderance value for the year June 02 to May 03 (Table - 2.3). Insects are

regular food items throughout the experimental period with the maximum index in

October (16.00) and minimum was found in May (8.26). Next level of preference

was molluscan form; it appeared maximum in July (23.10) and minimum in

February (5.21). Third level of abundance was copepods which recorded a

maximum in September (18.32) and minimum in June (11.05) than the rotifers

during the entire period (Max: January 6.32, Min: June 0.45). Fourth level of

abundance was recorded for algae (Max: October 16.00, Min: May 8.26), and small

fishes which found max in February (20.12) and minimum in August (0.10).

18

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Annelid worm (Max: April (8.00), Mm: August (2.34) had high value of average

when compared to the cladocerans. Finally, detritus matter and unknown matters

were recorded throughout the year.

2.5. Feeding Intensity

Feeding intensity of M. gulio data were depicted in the form of Fig -

2.1. Occurrence of full gut was seen during January (78%) and 3/4 gut was observed

in July (32%) whereas the presence of ½ gut was seen in April (48%). Dominance of

1/4 guts was recorded in August (26%) and no ¼ gut was found in December,

January and February. Guts with no food were encountered during September

(40%). The intensity of feeding index (Table-2.4) was more in January to February

(90.5%-91.5%). Very low feeding index was recorded during the September and

August (40% and 44% respectively).

2. 6. Discussion

The adaptation of the alimentary canal of fishes to their food is particularly evidenced

in the form of mouth, size, shape and structure of the orophamx, dentition, gill

rackers, structure of the esophagus, and shape of stomach and relative length of the

gut. The alimentary canal shows variation and modifications in accordance with the

feeding habits of different fishes. The mouth positions were determined by the

feeding habit of particular fish. The sub terminal mouth noticed in M. gulio was well

adopted for column feeding habit (Gupta et al., 1999). Carnivorous fishes have strong

teeth, jaws and long gill rackers in contrast herbivores are characterized by absence of

19

Fig 2.1 Percentage of food items of M. gulio Present in different months

Jun July Aug Sep oct Nov Dec Jan Feb Mar Apr May

Months

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teeth (Shafi, 2000). Adults of M. gulio possess moderately strong, jaws, gills with less

and moderately long and sub terminal mouth which distinguish the omnivorous

mode of feeding habits.

Coiling of intestine is a prominent index to distinguish the feeding habit of fishes

(coiled condition - herbivores; straight condition - carnivores). According to Khanna

(1961) gut of predatory or carnivorous fish has short intestine, in contrast to

omnivores and herbivores, which have long coiled intestine. Straight type of intestine

was seen in M.gulio which indicating carnivorous type of feeding. Another important

factor is relative length of gut (RLG) to determine feeding habits of fishes (Sharma

(1986); Datta Dasgupta (1986); Bose and Islam (1986); De and Dasgupta (1995, 1997)

and North (1996). RLG value of M. gulio was found as 0.67. Some carnivorous fishes

like Channa spp, (Das & Moitra 1956; Das gupta, 2000) and herbivorous fishes like

Labeo rohita and L. genius, the RLG were about 12.0 and 9.5 respectively (Das and

Moitra 1995). In omnivorous fishes, (Das & Nath, 1965) RLG values were lower e.g.

Pun tias conchonius (3.3) and Barbus hexastichus (2.3); the carnivorous fishes (Bagariouis

bagarious and Notopterous chittala) were found to have RLG 0.8 and 0.4 respectively.

No doubt, RLG value of M. gulio indicated carnivorous type of feeding (Das and

Moitra, 1965). David (1963) and Yusuf, and Majumdar (1993) reported M. gulio from

open water of Kulti and Matlah estuaries and indicated the fish as omnivorous. In the

present study, M. gulio RLG was between herbivorous and carnivorous values

supporting omnivorous type of feeding. Nikolsky (1963) classified the food into four

different categories according to important of food items present in the diet of fish.

1) Basic food (normally eaten by fish and comprises most of the gut contents), 2)

Secondary food (frequently found in the gut), 3) Incidental food (rarely found), 4)

obligatory food (absence of basic food items). In accordance with above categories, M.

gulio comes under basic food level, because in most of the months the gut was filled

insects, molluscs, and copepods.

Considerably the seasonal variation of feeding percentage M. gulio indicated

identical feeding habitation i.e., consuming more or less same type of food items. Vast

proportion of food items consisted insects, copepods, small fish and algae, which

indicated the selection of euryphagic (feeding on variety of food) nature of feeding

habits. It appeared that among the same food groups, if any one of the food decreased,

another food item of the same group componsated it. This feeding habit indicates that

the fish lives in the same habitat environment without any competition or without

scarcity of food.

Feeding intensity of M. gulio was found to be higher during January and

February. Feeding intensity was very much influenced by maturity of gonads,

spawning and the availability of food items (Khan et al., 1998; Kashava et al., 1988;

Geetha et al., 1990; Pandian and Rahman, 1999; Rao et al., 1998). In the present study

during spawning season (Aug-Sep) percentage of empty gut was more Kader et al.,

(1988) reported their empty stomach in gravid females indicating starvation. This

cessation of feeding by gravid females may be attributed to the occupation of the

coelomic cavity by the fully matured swollen ovary cells. In the case of males, they do

not undergo fasting due to narrow testis. Khan (1988) reported that freshwater carp

21

Cyprinus macrostomus undergoes starvation or empty guts are found during the

breeding season. Generally feeding intensity was found to be very low during pre -

spawning and spawning seasons while it was high during post - spawning and at

maturity time of gonads because at that time more energy is needed for development

of the gonads. Pandian, (1966) reported intensive feeding to yield energy for metabolic

process of the fishes. Highest feeding intensity was recorded in January and February

which represented the gonad maturing time (Chapter - IV) .which requires vigorous

feeding to ensure vitellogenesis for the next breeding season. Lower feeding intensity

found during Auguest - September indicated the spawning season of M. gulio

(Chapter - III). Geevarghese (1976, 1984) observed similar phenomenon in Glassayobius

giuris and Ologolepis actipennis. Lagler et al., (1982) has suggested that feeding intensity

was limited by light, temperature, pH, salinity and internal rhythm that may exist. The

present study on food and feeding habits of M. gulio revealed that it is a column feeder

and basic food feeder with euryphagic mode of feeding.

22