Feeding preferences in two tropical omnivorous fishes, Oreochromis shiranus and Barbus paludinosus were similar when offered an array of planktonic food in aquaria. The two species were stocked into earthen ponds at different rates. Abiotic and biotic variables were measured over a period of 120 days. Data analysis by multiple linear regression did not reveal significant negative coefficients between adjacent trophic levels, which would have indicated top-down effects. It is suggested that the results are due to uncoupling between trophic levels in tropical freshwater ecosystems.