Growth performance of Labeo bata (Hamilton, 1822) in freshwater and its acclimatization in brackish water with betaine as feed additive

Abstract Climate change is one of the major causes of coastal flood and tropical cyclone which results in salinity changes in large scale coastal area. Salinity affects survival and growth of many aquatic organisms and causes stress of freshwater fish affecting fisheries in various parts of the world. However, incorporation of ‘Betaine'in the supplementary feed may be way out for freshwater fish species grown in saline environment. In this study, the experiments were conducted with Labeo bata , a freshwater fish species with two feeds, T0 (non-betaine feed) and T1 (betaine added feed) in three phases: (i) growth study for 50 days in freshwater, (ii) toxicity test on salinity for 96 h, with loss of body weight and muscle tissue water, and (iii) salinity resistance test for 12 days in gradually increasing salinities @ 1.0 ppt day −1 . Results showed that growth rate (%) was significantly (p˂0.05) higher in betaine fed fish (16.79 ± 0.84–27.91 ± 3.33) as compared to non-betaine fed fish (13.58 ± 1.25–15.36 ± 0.29) throughout the experimental period. Betaine fed fish showed no mortality even at 12 ppt after 96 h exposure whereas all non-betaine fed fish showed 100% mortality within 24 h at 12 ppt. Over all, non-betaine fed fish lost 10.3% higher amount of water in muscle tissue as compared to that in betaine fed fish while grown in saline condition. The beneficial effect of betaine as feed additive described in this study may encourage farmers to culture L. bata up to 12 ppt.