光照时间对黄鳝生长及性腺发育的影响

Female rice field eel, Monopterus albus(25.5±0.7 g) in the yong stage were exposed to five replicated photoperiod treatments（24D, 6L:18D, 18L:6D, 24L and natural photoperiod where D= dark hours, L = light hours）in order to investigate the effect on growth and gonadal development during the conditioning process from 19, June to 21, July 2008. The weight gain(WG), specific growth rate(SGRW) and gonadosomatic index(GSI) were examined at the day of 42 and the end of experiment. The study showed that the continuous dark (24D) resulted in the greatest WG and SGRW (P＜0.05) at the day of 42 and the end of experiment, respectively. In the constant long photoperiod(18L:6D) , the weight gain was inhibited but the GSI was the greater than any other photoperiod treatments at the end of experiment（P＜0.05）, which suggested the gonadal development was improved significantly in the condition. The 24-h photophase inhibited both the growth and GSI significantly, moreover, comparing to the constant short photoperiod(6L:18D) or natural photoperiod, continuous dark (24D) resulted in the improved somatic growth and gonadal development, which were probablely related closely to the facts that rice-field eel has small and visually degenerated eyes, and naturally lives in habitats with faint light.