Feed utilization, growth and survival of Clarias gariepinus (Burchell 1822) fingerlings cultured under different photoperiods

This study assessed the effects of three photoperiods on growth, feed utilization and survival of African catfish, Clarias gariepinus fingerlings. Fish of initial weight 1.15 +/- 0.03 g(mean +/- SEM) were exposed to 24 h of darkness (DD), 12 h of darkness and 12 h of light (DL) and 24 h of light (LL) for a period of 70 days in a partial flow-through system. The fingerlings were cultured in triplicate groups and fed on 35% crude protein prepared diet at 5% body weight. Fingerlings reared in darkness (DD) had significantly (P<0.05) highest feed intake, weight gain, protein efficiency ratio, specific growth rate and percentage survival followed by fingerlings cultured in DL which were significantly (P<0.05) higher than those in LL Also, the fingerlings cultured in DD had significantly (P0.05) lowest uneaten feed and feed conversion ratio, than those reared in DL and LL There were no significant (P>0.05) differences in the water temperature and pH of fingerlings cultured under the three different photoperiods, however, dissolved oxygen concentration was significantly (P<0.05) reduced when the fingerlings were cultured in 24 hour darkness. Fish cultured in DD had darker skin colorations than those in LL The results of this study show that growth, feed utilization and survival of C. gariepinus fingerlings were improved when cultured in 24 h of darkness. (C) 2008 Elsevier B.V. All rights reserved.