RESUMO
The content of the digestive tract of 4 authoctonous species of fishes that presented characteristics of larvivorous fishes was analyzed. It was found that 28% of the caught specimens of Aequidens pulcher presented in their gastrointestinal content residues of larvae and pupae of mosquitoes combined with other food, and that 26 5 has only larvae and pupae. In Aequidens coeruleopunctatus, 6 % of their content was larvae and pupae with other food, whereas 10% had only larvae and pupae. 56% of the Poecilia caucana specimens had larvae and pupae with other food, and 34% only larvae and pupae. Poecilia reticulata contained larvae and pupae with other food in 62% and 33% only had larvae and pupae. These results show an effective bioregulator activity in these fishes identified as larvivorous under natural conditions.