Excerpt from the Terminal Report on the NACA Project1 - Library

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Techniques were successfully developed for <strong>the</strong> breeding and culture of Ompok bimaculatus, Wallago attu and Clarias batrachus. All three species can be bred through hormone administration. Clarias batrachus was spawned by a single dose of 30 mg of Indian major carp pituitary or 4 000 I.U. of HCG/kg of female only. The maturity of this fish was substantially advanced through implantation of LHRH pellets. Through proper broodstock management and hormone treatment, it was possible to breed this fish <strong>from</strong> April to October, covering pre-breeding, breeding and postbreeding seasons. Mini hatcheries were set up for this species at two centres. Molluscan meat was found to be suitable for both Wallago and Ompok. Mystus seenghala, ano<strong>the</strong>r catfish taken up for culture, was found to feed nocturnally during late evening and <strong>the</strong> early night hours. It showed a marked preference for fish flesh, followed by prawns and molluscs. 9. Prawn breeding and culture Laboratory-reared seed of Macrobrachium rosenbergii produced in October 1988 attained first maturity in June 1989 and berried prawns were observed until September 1989. Meat of freshwater mussel was exclusively used as larval diet. Larval mortality in outdoor rearing could be minimized by using a chemo<strong>the</strong>rapeutic drug. These findings could be applied in <strong>the</strong> management of giant freshwater prawn hatcheries in India. 10. Culture of freshwater molluscs The pearl mussels, Lamellidens marginalis and L. corrianus, recorded a survival of 83 % when suspended at pond surface, as against only 13 % when set at <strong>the</strong> bottom. The highly migratory nature of Achatina fulica, Pila spp., and Laevicaulis alte could be curbed by employing simple metallic copper or copper sulphate barriers. 11. Fish breeding Intraperitoneal injection of pimozide, a dopamine antagonist, at 10 mg/kg 4 h prior to <strong>the</strong> administration of LHRH-A at 20u/kg body weight, was highly effective in <strong>the</strong> induced spawning of catla, rohu and mrigal. Administration of Winstrol, an anabolic steroid, at 4 mg/kg/month <strong>from</strong> May to July 1989 to mature rohu led to <strong>the</strong> development of <strong>the</strong> highest number of oocytes and highest percentage of fertilization, as compared to progesterone-treated and control groups. This indicated that Winstrol could be used as an inducer for final oocyte maturation. 3. The Regional Lead Centre in Thailand (RLCT) 1. Channa striatus culture system A survey was carried out to study <strong>the</strong> artisanal practices of Channa striata culture, <strong>the</strong>ir problems and economic aspects. Detailed laboratory studies were later conducted to assess <strong>the</strong> lipid and vitamin requirements of snakehead fingerlings. The optimum level of dietary lipid and vitamin requirements of snakehead fingerlings. The optimum level of dietary lipid was found to be 6 % and no significant difference could be seen in survival, growth and conversion
etween <strong>the</strong> lipid sources tried, viz., soybean oil, Trichogaster oil and Pangasius oil. Panto<strong>the</strong>nic acid was found to be a particularly important vitamin for snakehead growth and survival. 2. Macrobrachium culture system By filtering <strong>the</strong> culture water through carbon and EDTA, it was possible to reduce <strong>the</strong> high rate of mortality of Macrobrachium rosenbergii postlarvae in hatcheries significantly. In trying to understand <strong>the</strong> effect of water quality on larval survival, a study on acute toxicity of ammonia was conducted, which revealed <strong>the</strong> 48 hours Lc 50 values for 5, 12, 23 and 35-day old larvae to be 1.53, 1.85, 2.05 and 1.77 ppm of unionized ammonia respectively. A system-oriented and multidisciplinary research programme was conducted on <strong>the</strong> grow-out aspect of <strong>the</strong> Macrobrachium culture system, including studies on stocking density, feed and feeding, fertilization and environmental changes. A small-scale hatchery successfully produced juveniles of this prawn using saline water prepared <strong>from</strong> salt-pan residues and 71–90 % survival <strong>from</strong> larval to juvenile stage was achieved. The great practical application of this would be Macrobrachium culture fur<strong>the</strong>r inland <strong>from</strong> <strong>the</strong> coastal region. An experiment conducted in grow-out ponds revealed that aeration had no effect on Macrobrachium production at a low stocking density of 6 individuals/m 2 , <strong>the</strong> mean stocking weight being 4.18 g. On <strong>the</strong> o<strong>the</strong>r hand, intrinsic biological characteristics (large variations in sex ratio and male phenotypes) greatly affected <strong>the</strong> yield and market values. The average yield over a seven-month cycle amounted to 1 312 kg/ha, which gave a net income of $US 1 890, with 41 % profitability. In experiments to ascertain <strong>the</strong> vitamin requirements of Macrobrachium, it was found that <strong>the</strong>re was no difference in its growth rate and survival when vitamins were fed at 0.5 %, 1.0% and 1.5%. However, <strong>the</strong> growth rate was faster than that of <strong>the</strong> control group, which was not given any vitamin premix. Likewise, <strong>the</strong>re was no significant difference in growth when prawns were fed at five levels of dietary protein, ranging <strong>from</strong> 20% to 40%. Sex differentiation in Macrobrachium generally took 100–120 days after hatching, but was observed to start in 70 days in fast growing individuals. Histopathological studies were made of prawns affected by some of <strong>the</strong> severe diseases encountered, viz., shell disease, idiopathic muscle necrosis and red discoloration disease. A variety of bacteria were isolated <strong>from</strong> <strong>the</strong> muscle tissue of prawns with red discoloration disease. 3. Catfish culture system Disease infestation is responsible for <strong>the</strong> high mortality in artisanal catfish culture which may have resulted <strong>from</strong> high feeding rates, intensive stocking and poor water management. Improvement of existing practices of fry production and separation of nursery and grow-out activities. The traditional use artificial feed to raise fry attained a survival rate of 20–30%; whereas, <strong>the</strong> use of natural food produced through application of poultry manure resulted in better growth and higher survival of fry at 50%. Using large fingerlings in grow-out operation, it was possible to reduce <strong>the</strong> mortality rate <strong>from</strong> 60– 90% to only 30% and achieve a yield of 37.5 t/ha in three months. This yield is comparable to that obtained by farmers in ponds with continuous water flow.
Page 1 and 2: Excerpt fr
Page 3 and 4: Priority was thus given to producin
Page 5 and 6: The computerized AQUIS, a numerical
Page 7 and 8: present traditional with intensive
Page 9 and 10: Attachment A: Research under <stron
Page 11 and 12: With grass carp as the</str
Page 13 and 14: • gingili oil cake + groundnut oi
Page 15 and 16: phosphate + multivitamins) with 30%
Page 17: Feeding frequency appeared to influ
Page 21 and 22: Preliminary studies showed that pad
Page 23 and 24: Short-necked clam was successfully
Page 25 and 26: Attachment B: Training courses and
Page 27 and 28: While all the succ
Page 29: 6. Workshops Two workshops were org

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