Studies On Nursery Rearing of Genetically Improved Farmed Tilapia (Gift) In Bio-Secured Raceway Systems in India

Abstract

A series of trials were conducted on "Intensive nursery rearing of GIFT in raceway systems" at TNFU, Madhavaram Chennai campus. GIFT seeds (initial length: 1-1.5 cm; weight: 0.3 to 0.4g) were stocked at the rate of 75 to 100 fish/m' in 40m capacity raceways. The effect of aerobic microbial floc (AMF), dietary protein levels and water temperature were studied. In the AMF driven raceway system, near 100% survival and 10-fold weight increment was achieved for GIFT fry in 15-days. Secondly, GIFT seeds (initial length, 5.5-6 cm; weight: 3 to 4g) were transferred from the previous trial and stocked at a density of 75 fish/m and two dietary crude protein levels of 26% and 38% were tested over duration of 55 days. Better growth and production biomass (32-36% higher) in lesser DOC (15% lower) was obtained in the high protein diet fed group. Comparison of growth performance of previous trials with a separate batch of fish which were grown under thermo-regulated water conditions at 30-32 °C showed that an increase in water temperature by 4-5 °C enhanced the growth rate of GIFT by 20% during the 10 week culture period. In summary, advanced aquaculture systems such as bio-secured raceways and technologies like AMF driven zero-water exchange systems and thermo-regulated systems can be effectively utilized for large scale high-density nursery rearing of GIFT in Indian conditions.