ISRAELI JOURNAL OF AQUACULTURE-BAMIDGEH, vol.55, no.2, pp.132-138, 2003 (SCI-Expanded)
A feeding experiment was carried out in a brackish water (18 ppt) flow-through system to determine
the effects of different photoperiods (light hours/dark hours; L/D) on feed intake and growth
performance of young rainbow trout (Oncorhynchus mykiss). Duplicate groups of fish (35.32 g
avg body wt) were exposed to a natural photoperiod, a long photoperiod (16L/8D) or a continuous
photoperiod (24L/0D) for 60 days and fed to satiation twice a day. The growth rate, daily feed
intake and feeding rate in the natural photoperiod were significantly lower (p<0.05) than in the
long and continuous photoperiod groups. Growth was highest in the continuous photoperiod, but
did not significantly differ from the long photoperiod. The feed conversion ratio, feed efficiency
and gross efficiency in the long and continuous photoperiods were slightly better (about 5-7%)
but did not significantly differ (p>0.05) from the natural photoperiod. Survival was not significantly
(p>0.05) affected by the treatment. For better growth and a lower food conversion rate, the long
photoperiod is recommended for young rainbow trout.