Effects of Predation by Tucunaré (Cichla ocellaris) on Tilapia nilotica in Ponds

Abstract

Three ponds were stocked with 3,000 Tilapia nilotica (6-7 cm total length) per hectare, and 17 days later with tucunaré (2-3 cm total length) at 380, 380, or 790 fish/ha. After 124 days, survival of tucunare was 26-30% and they averaged 191 g, 21 g, and 17 g, respectively. Growth of tucunare was related to availability of prey, i.e., tilapia recruits, and density of predators. Tucunaré in two ponds had equal densities at harvest but grew at substantially different rates probably because of differential rates of mortality. Total fish production was 71% less in the pond with the largest tucunaré than in the other two ponds. The decrease in tilapia biomass by predation resulted in a decrease in total fish production.