Central Institute of Freshwater Aquaculture
(Indian Council of Agricultural Research)
Bhubaneswar, Orissa, India
I. Establishment of the Centre and Its Facilities
The Regional Lead Centre in India, located in Bhubaneswar, Orissa, has been supplied with a power line to insure continuous power supply. Necessary changes in the transformer are being done to obtain uniform high voltage, and it is expected that telephone and telex lines will be set up before the end of the year. Work on the reconstruction and repair of the flood-damaged ponds has been initiated and ponds (0.04–0.40 ha in size) will soon be available.
The scientific work of the Centre is organized under nine major divisions:
Production technology
Fish breeding and genetics
Soil and water environment
Fish nutrition
Pathology
Fish physiology
Aquaculture engineering
Economics and statistics
Extension
II. Research Activity
A. Disciplinary Research
1. Genetic Laboratory
Inter-generic hybrids between Indian and exotic carps were produced by crossing common carp females with Indian major carp males. Rearing of individual crosses showed better growth in monoculture than polyculture. The hybrids also showed lower seine escapability (23.3–77.1 per cent) than common carp (80.2 per cent) but higher than catla (20 per cent). A study of the ploidy status of common carp x catla hybrids indicated them to be triploids with chromosome numbers varying from 75 to 76.
The inter-generic hybrids between Indian carps, rohu x catla attained their first maturity when three years old as against two years for their parents. The hybrid females were back-crossed with rohu males. Studies on the growth potential of the three hybrids could not be concluded due to low survival rates in some ponds. However, survival as high as 92.5 per cent indicates possibilities of their commercial production.
Progress was also made on studies on genetic engineering. Gynogenetic (G2) progeny of mrigal was produced and a part of it fed with a diet of methyl testosterone for induction of sex reversal. About 5,000 triploids and 36,000 tetraploids of rohu were also produced. The rate of incidence of triploidy and tetraploidy ranged between 25–40 per cent and 40–80 per cent respectively.
2. Nutrition Laboratory
Protein requirements of grass carp and catla fingerlings were found to be 36 and 40 per cent respectively at 30–34°C. A formulated diet comprising plant proteins, rice bran and fish meal fortified with vitamins, minerals and trace elements was used for the former while a synthetic diet consisting of casein, gelatin, dextrin, cellulose, carboxyl methyl cellulose, soyabean oil, minerals, vitamins and trace elements for the latter.
Studies on protein utilization and buget were also conducted using the fry (0.36–0.75 g) of the three Indian major carps - catla, rohu and mrigal - at 22–31°C. Four practical diets containing groundnut oilcake, fishmeal, rice bran, dicalcium phosphate, vitamins, trace elements and sodium chloride with dietary protein levels of 30, 35, 40 ad 45 per cent were employed for this study. Rohu and mrigal attained the maximum growth with 40 per cent while catla with 45 per cent protein diet. Specific growth rate, protein retention values and Protein Efficiency Rate (PER) were the highest for rohu and mrigal at 40 per cent diet and for catla at 45 per cent; while the trophic coefficient was the lowest at these levels. Again, protein assimilation (87.26 and 93.89 per cent) and urinary nitrogenous excretion (79.12 and 77.74 per cent) values were the highest for rohu and mrigal with 40 per cent protein diet and for catla (94.75 and 88.99 per cent) with 45 per cent. These diets also showed the best efficiency of meat production (EMP), meat produced in assimilation (MPA) and protein produced in assimilated protein (PAP).
Protein requirements of silver carp fry (1.03–1.35 g) were found to be 31 per cent at 29°C. At 27.5–29.5°C, a diet containing 42 per cent protein gave the best growth and feed conversion ratio for silver fingerlings.
3. Disease Laboratory
The most common parasites in fish ponds and farms have been found to be myxosporidians, microsporidians and Argulus. Acute argulosis caused epidermal lacerations and mortality in broodstock ponds, especially in rohu. Pond treatment with 0.25 ppm (a.i.) malathion followed by dip treatment in potassium permanganate solution (500 ppm) for a minute were found to be effective in controlling the parasite and secondary microbial infection at the site of ulceration. Though the parasite is totally eradicated within a week, it was noted that three successive treatments are required at weekly intervals to prevent its recurrence. LC50 value of malathion for rohu was estimated at 2.5 ppm.
An acute case of fish disease outbreak at Nonepur Fish Farm (Orissa) was investigated. While rohu and mrigal suffered from argulosis, catla had an attack of bacteraemia. Based on drug sensitivity tests on isolated bacterial strains, oxytetracycline therapy was suggested; this had a salutary effect.
An outbreak of ulcerative disease in catla involving A. hydrophila was also investigated. The damage appeared topical as even after several attempts, no bacteria could be isolated from heart or kidney. Dip treatment in 1000 ppm potassium permanganate solution gave the best results.
Histopathological and haematological studies are in progress.
A new cell line, fibroblast in character and secretory in nature, has been developed from hepatoma of silver carp and is now passing through 14th passage of sub-cultivation.
4. Physiology Laboratory
Studies on protein, lipid and energy digestibility of feed ingredients and formulated feeds showed that grass carp fingerlings digested 84.5 per cent protein from a salseed cake fortified diet comprising groundnut oilcake, rice bran, trace minerals and vitamin mix while digesting only 71.9 per cent from rice bran. However, mrigal yearlings registered lower digestibility (73.9 per cent) with the formulated feed than grass carp but higher (86.6 per cent) with rice bran.
Lipid and energy digestibility of vitamins-trace minerals, fortified groundnut oilcake and rice polish pelleted diet and groundnut oilcake in mrigal yearlings ranged from 89.9–92.1 per cent and 96.4 per cent, and 78.6 per cent and 92.8 per cent respectively. However, lipid digestibility (91.3–96.9 per cent) of groundnut oilcake in grass fingerlings was about the same as in mrigal but digestible energy both in salseed (74.8 per cent) and sesame oilcake (89.6 per cent) was lower than mrigal (91.6 per cent and 1,901 kcal/kg. respectively).
Administration of progesterone and an anabolic steroid Winstrol, each at 4 mg/kg/month from May to July in mature rohu indicated that Winstrol-treated female rohu developed the highest percentage of oocytes containing 70 per cent nuclear migration six hours after the first injection. Though the diameter of the ovarian eggs did not show any significant difference between control, progesterone and Winstrol treated fishes, the percentage of fertilization was the highest in the last group, suggesting that Winstrol anabolic steroid could be used as a potential inducer for final oocyte maturation.
Pimozide, a dopamine antagonist was used in combination with superactive analogue of LHRH for spawning the Indian major carps. It was observed that intraperitoneal injection of pimozide at 10 mg/kg four hours prior to LHRH-A at 20/ug/kg body weight was highly effective. A minimum of 15 sets each of catla, rohu and mrigal were successfully spawned.
Estimation of Thyroxine (T4) in fish serum has been standardized with RIA using I1 2 5 as radio tracer. The seasonal estimation of thyrozine is being correlated with gonadal development.
B. Interdisciplinary Research
1. Broodstock Management
Studies on broodstock management were further modified. Of the eight 0.1-ha ponds, six were stocked with a combination of catla 3:rohu 2:mrigal 2:grass carp 2:silver carp 1; and two with the same combination in equal proportions. The fishes were fed at 3 per cent of their body weight with a formulated diet containing 30 per cent protein. Grass carp were fed at 20–25 per cent of their body weight with aquatic vegetation. Gonadal development of all the carps was better than in previous experiments and the fish could be spawned as early as April. The results are being analyzed.
2. Catfish Culture
Both Wallago and Ompok were bred through hormone administration. Studies on temporal variations in feeding habits of Mystus seenghala indicated that they are nocturnal feeders, feeding actively during late evening and early night hours. Their food preferences were also investigated using fish, prawns, molluscs and a pelletized diet (35 per cent protein) which showed a marked preference for fish flesh followed by prawn and molluscs. Clarias was also spawned in the laboratory and its rearing techniques are being further studied.
3. Soil and Water Management in Undrainable Ponds
Studies on the nature and composition of humus in the sediment of fish ponds from different ecological zones indicated the total humus content to range from 0.126 to 0.436 per cent constituting 18–33 per cent of the total organic content. The nitrogen contribution by humus towards total nitrogen content of the soil varied from 34.4 to 60.3 per cent of which humic acid and fulvic acid contributed 20.9 and 23.8 per cent respectively. Among the different fractions of humus, fulvic acid was found to be the dominant fraction in most soils.
Nitrogen fixation rates in the water phase of an old and large rural undrainable pond (one ha), small newly-excavated rural pond (0.2 ha) and a carp-rearing pond (0.1 ha) at CIFA ranged from 0.197–16.70, 2.50–14.60 and 3.30–15.3μgN/m3/h. The activity was high in January but low in November. These levels are low as compared to those in temperate countries and suggest the scope for improving nitrogen fixation rates through environmental manipulation. In this connection, laboratory and field culture of Anabaena and Azolla respectively are in progress.
Monoculture of rohu with an additional periphytic substrate comprising coconut palm leaves and covering about 7 per cent of the pond surface area indicated an increase of 13 per cent (283.4 kg/ha) and 30 per cent (350 kg/ha) respectively at 2000 and 3000/ha in four months' rearing over the production rates obtained from ponds without it. Monoculture of mrigal at 4000/ha resulted in 70 per cent higher production than that at 2000/ha in four months'rearing.
Preliminary observations on the quantification of detritus formation rates in the stocking, rearing and nursery ponds in the surface and bottom waters showed respective ranges of 1.76–3.28 and 3.11–5.32, 2.38–3.65 and 3.66–4.87 and 0.91–1.52 and 1.84–3.50 mg/cm2/d respectively.
III. Training and Extension Activities
The annual training programme for senior aquaculturists was organized. A training programme which provided field experience was organized for eight ARS probationers. The Centre also organized a training programme on fish hybridization for officials of the Directorate of Fisheries, Tamil Nadu; and another on Clarias breeding and rearing for government officials of West Bengal. Demonstrations were organized for 367 farmers and field officers.
The Krishi Vigyan Kendra organized an on-campus training programme for 319 farmers and off-campus training programme for 541 farmers. The Trainers' Training Centre implemented a programme for 97 extension officials and others during the year.
IV. Information System
The Computer HP 3000 is being maintained by the Computer Maintenance Corporation Ltd., which is trying to stabilize the machine in working condition. About 200 AQUIS data sheets are now ready for storage.
