Depredation of Tilapia Fry by Dragonfly Nymphs and a Means for Control

Abstract

Dragonfly nymphs readily prey on Tilapia nilotica fry. In plastic pools (10 m², 0.8 m deep) stocked with equal numbers of dragonfly nymphs and tilapia fry, survival of fry was 51% higher in pools treated with methyl parathion, than in untreated pools. Applying 0.25 p/m active ingredient of methyl parathion 3 days before stocking fry killed all dragonfly nymphs with no apparent direct effects on fry survival or growth.