The toxicity of nonyl phenol ethoxylate to the developmental stages of the rainbow trout, <i>Salmo gairdnerii</i> Richardson

Abstract

SUMMARY Successive developmental stages of Salmo gairdnerii showed marked differences in their resistance to the action of the non‐ionic surfactant, nonyl phenol ethoxylate. The alevins, immediately after hatching, were highly resistant and survived concentrations of up to 42 p.p.m. for 6 hr. This resistance gradually decreased with the absorption of the yolk sac: when the yolk had been completely absorbed and before the fry had fed the lethal concentration was 2·5 p.p.m. After several days of feeding, resistance slightly increased but showed no further rise after 15 days. A concentration of 5·2 p.p.m. of nonyl phenol ethoxylate for 6 hr. was toxic both to 40‐ and to 210‐day‐old fish. It is considered that these changes in resistance are not correlated with changes in respiratory activity of the fish but with their water metabolism.