Effect of Salinity at Different Temperature Regimes on Growth of Cyprinus carpio (Linn.) Fingerlings

The present study was undertaken to determine the effects of five different salinities (0 ppt, 1.5 ppt, 3 ppt, 6 ppt and 12 ppt) on growth of common carp for 60 days at three different temperature regimes. The experiment was conducted in aquaria of 38 litres capacity fitted with complete aeration and filtration system, with 10 fishes in each, at air temperature ranges from 31.0°C-37.5°C (high), 23.0°C-31.0°C (mild) and 13.5°C-19.0°C (low) in triplicate. Growth in terms of average daily gain (ADG), net weight gain (NWG) and specific growth rate (SGR) were estimated on weekly basis. The fingerlings adapted well to the saline environment upto 6 ppt but 100% mortality was observed in 12 ppt at high and mild temperature regimes while 50% survival was recorded at low temperature. The decreasing trend of ADG, NWG and SGR were observed in fingerlings from 0 to 12 ppt salinity. Maximum ADG was reported in 0 ppt salinity followed by 1.5 ppt, 3 ppt, 6 ppt and 12ppt. At all the temperature regimes, as salinity increases the NWG of carp fingerlings similarly decreased like ADG. The highest SGR was recorded in 0 ppt salinity and followed by 1.5 ppt>3 ppt>6 ppt at mild temperature. The highest SGR (1.70±0.01%) was detected on 15^th day at 0 ppt while the lowest SGR (0.44±0.04%) was reported on 60^th day in 6 ppt salinity at mild temperature. The differences were statistically significant (p≤0.05) among salinities. The present findings demonstrate that environmental salinity affects the growth of carp fingerlings, with maximum growth in freshwater and declined with ascending levels of salinities at different temperature regimes upto 6 ppt salinity.