Effect of azolla-incorporated diets on the growth and survival of Labeo fimbriatus during fry-to-fingerling rearing

An experiment of 75 days duration was conducted in fertilized outdoor circular cement tanks (1,000 L) with soil base for evaluating the growth and survival of Labeo fimbriatus fry fed with pelleted feed containing varied levels of dried azolla (Azolla pinnata). The Control feed contained 45% groundnut oilcake plus 45% rice bran and 10% finger millet flour added as binder for pelleting. Dried azolla powder was incorporated into the feed at 10, 20, 30 and 40% levels, replacing the groundnut cake and rice bran proportionately. L. fimbriatus (mean length 2.42 cm) fry were stocked in all the tanks at 30 m−3. The fish were fed 10% of body weight during the first month, followed by 7% during the second month and 5% during the last 15 days. Incorporation of azolla did not affect (p > 0.05) the water quality, growth and survival of fingerlings at harvest. Incorporation of azolla in the diet reduced the cost of feed (Rs. per 100 g biomass; Rs: Indian rupee, INR; 1 INR ≈ 0.015 EUR) from 3.35 to 2.53, with a cost saving of 24.48%. The study indicated the possibility of incorporating azolla in diets of L. fimbriatus up to 40% during fry-to-fingerling rearing, resulting in savings on feed cost.