Effect of three photo periods on the growth of tilapian fish oreochromos aureus reared in glass tanks

Abstract EN

Fishes (Oreochromis aureus), with an initial weight of 17.14-18.57 g, were reared in laboratory glass tanks for 135 days to investigate growth under three photoperiodic regimes: LD 6:6, 12:12 and 24:0.

The fishes were stocked at a density of 100 fishlm3 , and fed once daily.

Every week, fishes were removed and weighted and water was changed using new dechlorinated water.

Photoperiod did not affect (P:;;0.05) the mean body weight, but the mean growth rates under LD 6:6 and LD 12:12 were higher than under LD 24:0, whereas the mean specific growth rate under LD 6:6 was lower than under the other two light periods.

However, during the first two months the body weight, growth rate (GR) and the specific growth rate (SGR) were the highest under LD 24:0, but then declined.

Body weight, GR and SGR became the highest under LD 12: 12 after the first two months until the end of the experiment.

The LD 6:6 resulted in the lowest values