In pens, the reductions in final weight, growth rate and PER attributable to CoP were
much lower than in aquaria. Fish fed the diet with 130 g kg 1 CoP had similar growth and
feed utilization compared to those fed the control diet (P>0.05) (Table 4; Fig. 1). The
results in pens concur with findings of Bayne et al. (1976) with tilapia and of Bautista et al.
(1999) with Cachamay (Colossoma sp. Piaractus sp.), who found similar growth in fish
fed diets containing CoP and control diets. The amount of feed that could be fed to the fish
decreased with increasing levels of CoP in the diet (260 and 390 g kg 1
). This is in