Influence of salinity on food consumption, growth and energy conversion efficiency of common carp ( Cyprinus carpio) fingerlings

Abstract

Food consumption, growth rate, digestibility, nitrogenous excretion rate and oxygen consumption rate of common carp ( Cyprinus carpio L.) fingerlings (5.6–8.8 cm in body length) were measured at salinities from 0.5 to 14.5%. at a temperature of 13.8–22.5 °C for 92 days. The specific growth rate in weight gain was high (2.32% day −1) in fresh water, reduced with increase in salinity, and reached a negative percentage at 10.5‰. The daily food consumption rate of the fingerlings was high (4.39 ± 1.53%) in fresh water and diminished with an increase in salinity up to 6.5‰. The fingerlings had a high digestibility (96.6 ± 1.99%) of dry matter in feed at a salinity of 2.5%. and in fresh water. The range of the nitrogenous excretion rate (μg N g −1 day −1) at various salinities varied as follows: 2.5%., 24.77 ± 11.36; fresh water, 41.51 ± 5.85; 4.5%., 55.69 ± 10.49; 6.5%., 64.75 ± 5.00; 8.5%., 101.20 ± 25.47; 10.5%., 130.96 ± 12.96. Oxygen consumption rate was low in fresh water and at 2.5%. salinity. The high growth rate in fresh water was correlated with the high daily food consumption rate and high digestibility of feed.