Growth, development and behaviour of Persian sturgeon Acipenser persicus larvae in different light regimes

The effects of five different light regimes on growth performance and behaviour of Persian Sturgeon larvae were examined. Larvae were reared under five different photoperiods (24L, 12L:12D, 16L:8D, 8L:16L and 24D), from hatching (25.8 +/- 8.1mg; 12 +/- 0.6mm) to 28days post-hatch (dph). Except the last week, there was no significant difference in growth parameters among the experimental groups. Growth performance significantly improved in larvae reared under a continuous light regime. The highest final length (34.5 +/- 1.7mm) was measured in 24L and the lowest one (29.5 +/- 0.4mm) in the constant darkness. Relative to other experimental groups, the continuous darkness had a retarding impact on the yolk sac absorption and swarming behaviour. Among the whole body compositions, the lowest body moisture content was measured in the continuous light group. Persian Sturgeon pre-larvae and larvae were not completely dependent on light regimes (in 1-21days), whereas on the basis of measured parameters (total length, wet and dry weight and digestive fullness index) a continuous light regime played a decisive role on growth performance beyond 21dph.