Effect of hatchery light condition on spawning and early development of Tilapia guineensis

Abstract

To determine the extent light stimuli could influence the spawning and larval performance of Tilapia guineensis, sexually matured T. guineensis were simultaneously paired to spawn and their larvae nursed in two hatcheries under different light (restricted – closed- and unrestricted-open-) conditions. Hatching of egg in the two hatcheries was compared. Growth of day five larvae in the two hatcheries at equal density of 10 larvae/l and uniform food and feeding regime were monitored for twenty days. Survival of larvae in the two hatcheries was analysed at the end of the study. Duration to spawning in the open hatchery (120 hours) was shorter than in the closed hatchery (132 hours), however the difference was not significant (P > 0.05). Also egg hatching in the hatcheries was not significant (P > 0.05). Larvae reared in the open hatchery grew significantly (P < 0.01) faster than larvae reared in the closed hatchery but the difference only appeared after day-8 post hatch. Larval survival 85% in the open hatchery which was significantly higher than 75% survival observed in larvae reared in the closed hatchery. The findings suggest involvement of visual sense in growth hormone surge, survival and chemosensory activity of spawning but not in egg hatching in Tilapia guineensis.