Abstract:
Long-day photoperiods are considered as an effective managerial tool in manipulating
fish growth and morphology in a number of fish species. In this study, three different
photoperiod regimes were exposed to Nile tilapia (Oreochromis niloticus) fry in order to
determine the fish survival. Besides that, the other purpose of this study is also to
investigate the effect of different photoperiods toward fish morphological changes. Fish
total length, TL fish body depth, BD and deformities were accessed at three different
photoperiod treatments of Tl(l2L:l2D), T2 ( l6L:8D), T3(24L:0D), and control. Growth
and development of the fries increased with increasing photoperiod duration in all
treatments throughout the two weeks experiment. The best performance for TL and BD
was recorded in treatment with continuous light (24L:0D). No deformities was observed
in all treatments conducted in this study. The highest percentage of survival rate was
recorded at photo period T3(24L:0D) and the lowest was at TI ( I 2L: l 2D). The results
from this study indicate that extended light increases the growth of Nile tilapia fry
because during this stage, the fish are more sensitive with light and also other
environmental factors.