Fish in three aquaria were assigned to each of the experimental
diets and fed to satiation twice daily. Bi-weekly feed consumption was recorded. Total
weight and number of fish in each aquarium were determined every 2 weeks. From
week five to 10, the aquaria were cleaned 1 h after the last feeding to remove remaining
diet or feces every day. The feces collector designed by the Tokyo University of
Fisheries Ogino et al., 1973 was installed instead of the normal siphoning column.