Can varying photoperiod regimes alter the growth response, behaviour and physiology of <i>Clarias gariepinus</i>?

To understand the welfare implication of photoperiod manipulation on Clarias gariepinus, fingerlings (n = 108) and juveniles C. gariepinus with a mean weight 3.75±0.03 g 21.7±2.88 were exposed to zero light (0L:24D)-T1, average (12L:12D)-T2 continuous (24L:0D)-T3 in triplicates for 35 days. The highest mortality rate was recorded T2 T3 (13.9%) (22.2%). T1 significantly higher (p 0.03) weekly growth gain (MWG). Specific Growth Rate (SGR) Feed Conversion Ratio (FCR) both juveniles. Lowest swimming observed while aggressive act, bruises, scars (58.6 mg/dl 56.9 mg/dl) plasma glucose found fish categories. There no significant differences (P 0.11) among cortisol levels categories at different regimes. Fingerlings 24-hour darkness had MWG, survival rate, SGR FCR without any physiological stress. A regime is recommended culture boost production Aquaculture sector.