Increasing fish production in Tamil Nadu through production and distribution of genetically improved Tilapia

• Availability of genetically improved tilapia (Nile tilapia) within Tamil Nadu in the natural system was surveyed; and noticed that the Nile tilapia was available in the natural tanks in Krishnagiri district, Vaigai reservoir, Sattanur reservoir and also in the fish culture ponds of farmers in Thanjavur district. More than 90% of landings in Vaigai reservoir were dominated by Nile Tilapia with an average weight of 1 to 1.5 kg. Around 40 to 50 % of landings at Sattanur Dam were dominated by Nile Tilapia with an average weight of 1.5 to 2.0 kg.
• Technique for the development of Tilapia broodstock, hapa breeding, sex reversal and larval rearing were standardized. Broodstocks were developed by stocking them in rearing hapas @ 6nos./m². Sex ratio maintained at 1:1. Hatchlings were fed with diet containing 17 methyl testosterone hormone with shrimp starter feed for a period of 21 days. Two dosages of hormone (50 mg/kg and 60 mg/kg) were tried for inducing sex reversal. Rearing of sex reversed tilapia was carried out by feeding with Artemia followed by pellet feed.

• Studying the effect of synthetic hormones on the induced spawning and in vitro fertilization in common carp

• Synthetic hormones viz. ovaprim and wova-FH injected into males and female at dose of 0.2 ml/kg and 0.3 ml/kg of the body weight, respectively had induced the spawning after 9 h of hormone administration
• Fertilization rate of ovaprim was 79.18%, wova–FH was 81.46% and control was 85.11%. The highest rate of hatching was achieved in ovaprim (63.08%) followed by wova-FH (61.71%) and control (79.25%). The highest rate of survival was achieved in ovaprim (63%) followed by wova FH (60%) and control (79%).
• Synthetic hormone viz., ovaprim can be effectively utilized to produce induced breeding and in vitro fertilization of common carp during winter period. Using this technique continuous production of common carp seedlings is possible.

Mass production of triploid common carp (Cyprinus carpio) using chromosome manipulation techniques

• Synthetic hormone viz., wova-FH was injected intramuscularly to the brooders at the rate of 0.1ml/kg for male and 0.15 ml/kg for female. Induction of triplody was done by giving heat shock (39⁰C, 40⁰C and 41⁰C) for 1 min and cold shock at    (0-4⁰C) for 30 min, 45 min and 1 h after 9 min post fertilization.
• Fertilization rate ranged from 72.0-86.5%. Induction of triploidy using heat shock and cold shock was successful. The percentage of hatching of heat shock treated group was 63.5% at 39⁰C, 58.0% at 40⁰C and 50.0% at 41⁰C. The percentage of hatching of cold shock treated group was 53.0% at 0-4⁰C for        30 min, 44.0% for 45 min and 36.0% for 1 h.

Efficacy of JR200 on growth performance, health, immunity of tiger shrimp Penaeus monodon during experimentally induced Vibriosis

• The effect of immunostimulant (JR 200, provided by M/s. Kemin Industries) supplemented diet on shrimp growth, survival and some hemato-immunological parameters was tested after an experimental challenge with harveyi in different concentrations. The LC₅₀ value determined against V. harveyi was 3.98 x 10⁶ CFU/ml. There was a significant difference between the treatment groups and control group at p<0.05.
• JR-200, the product of M/s. Kemin has shown positive effects with respect to immune enhancement and growth related factors in shrimp juveniles,  which was also significant (p >0.05) over the control groups.