Effect of the Organophosphate Dylox on Rainbow Trout Larvae

Abstract

Organophosphate poisoning in fish and mammals has always been associated with the inhibition of acetylcholinesterase in both neuromuscular and brain tissues. This inhibition resulted in the apparent death of the organisms by asphyxia. Rarely have other effects been reported.In the present study, 1-inch rainbow trout larvae were treated for 16 hr with from 10 to 100 ppm Dylox, or for 40 hr with 5 ppm. This treatment produced a marked acetylcholinesterase inhibition that was reflected by their abnormal behaviour patterns. Histological examination revealed pathological changes in the heart, liver, blood cells, pseudogills, and muscular tissues; this pathology could not be explained on the basis of acetylcholinesterase inhibition.