author(s)
R Siju, VK Tiwari, Sunil Kumar Nayak and Babitha Rani

abstract
Effect of photoperiod on growth and survival of Clarias batrachus (Linnaeus, 1758) larvae were studied under Five different photoperiodic conditions: 24L (hrs. light):0D (hrs. dark) (T1), 18L: 6D (T2), 6L: 18D (T3), 0L: 24D (T4)), 12L: 12D (C). Average body weight (542.60±11.89 mg), specific growth rate (SGR) (7.43±0.04) and percentage weight gain (PWG) (4010.6±50.10) obtained in T3 (6L: 18D) photoperiodic condition was found to be significantly (p<0.05) higher than other treatments. The allometric coefficient “b” obtained is higher for T3 (6L: 18D) and T4 (0L: 24D) which indicates more larval growth potential. The polynomial 2-parameter model indicated the best fit to explain and predict body weight and length of larvae with the increase in age. Higher growth and survival is recorded in 6L:18D which can be attributed to better feed intake, higher melatonin synthesis and suppression of swimming activity and stress in dark condition. The photoperiod (6L: 18D) may be recommended as a simple, low-cost technique to maximize the hatchery production of C. batrachus larvae.