The effects of water temperature on the survival, feeding, and growth of the juveniles of Anguilla marmorata and A. bicolor pacifica

Abstract

In this study, we identified the effects of water temperatures on the survival, feeding, and growth of the juveniles of Anguilla marmorata and Anguilla bicolor pacifica which have been commercially cultured in southeastern China in recent years. Twelve groups of each species, each group of 20, were reared in 12 105-l tanks for 45days at six water temperature levels of 8, 13, 18, 23, 28 and 33°C (one level two groups). The results showed that A. marmorata all died within 10days at 8°C and most died at 13°C, but survived normally at temperature of ≥18°C. A. bicolor pacifica all died within 9days at 8°C and 20days at 13°C, and partly died at 18°C and 23°C, but survived normally at temperature of 28°C and 33°C during experiment. The maximum feeding rates of both species occurred at temperature of 33°C, being 2.23±0.10 % day−1 for A. marmorata and 2.41±0.06 % day−1 for A. bicolor pacifica. However, the maximum feed conversion rates occurred at 28°C, being 54.79±7.54 % for A. marmorata and 71.35±1.85 % for A. bicolor pacifica. The maximum daily weight gains (DWG) of both species, 2.63±0.12gday−1 for A. bicolor pacifica and 1.19±0.38gday−1 for A. marmorata, were also achieved at 28°C with initial and final mean body weights of 5.62±0.30g and 11.59±0.03g for the former and 4.97±0.36g and 7.18±0.80g for the latter. The DWG of A. bicolor pacifica was significantly higher (P<0.05) than A. marmorata at 28°C and 33°C. The specific growth rates of both species were positively correlated to water temperature (P<0.01). The optimal growth temperature is estimated to be 27.6°C for A. marmorata and 30.1°C for A. bicolor pacifica. We conclude that A. marmorata and A. bicolor pacifica survive and grow better at water temperature of 28–33°C than that of≤23°C. A. bicolor pacifica are more sensitive to low water temperature (≤23°C) than A. marmorata, but grow faster. Our results indicate that both species are suitable for commercial aquaculture, however the water temperature should be controlled relative higher.