In the present study, feed efficiency was affected by
water temperature, fish meal level, and their interaction
(Table 2). At 178C, feed efficiency was significantly
higher in fish fed the fish meal diets than fish fed the
all-plant-protein diet. However, the improved feed
efficiency in fish fed fish meal diets at 178C did not
result in significant increase in weight gain. The reason
for this is not clear. Although there were significant
differences in the weight gain of fish fed various levels
of fish meal at 218C and 278C, no significant
differences in feed efficiency were noted. This could
be caused by the variation in amounts of feed offered in
excess among tanks. Fish were fed to apparent satiation
by visual examination, but the slight excess of feed
remained, if any, was not removed from the tank.