The relationship of predator size to maximum prey size, and predator weight to weight of prey consumed among cannibalistic sea bass (Lates calcarifer Bloch) in a hatchery were assessed. Maximum prey size was computed from morphological measurements (predator mouth width, prey body depth and fish total length), while prey consumption was determined from predators kept in experimental beakers and fed only prey sea bass for a 7-day period. Maximum prey size was 61–67 % of predator total length (TL_prey = 0.5944 TL_predator+ 0.0724). Gut dissection of predators showed that size of ingested prey increased with increasing predator size not exceeding the maximum size limit indicated by the above equation. Daily prey consumption of predators in the beakers was expressed as W_Prey = -0.2407 W_predator+ 0.7697W_predator-0.1141. During hatchery rearing of sea bass, fish with length differences of more than 33 % must be separated and food of appropriate size provided to limit cannibalism.