Pathological Effects in Formalin-Treated Rainbow Trout (<i>Salmo gairdneri</i>)

Abstract

When rainbow trout (Salmo gairdneri) were exposed to 167 and 250 ppm formalin for 1 hr, moribund fish showed severe histopathological changes in gill epithelium. Hematocrit values and numbers of immature red blood cells were increased, suggesting a physiological response to hypoxia. The results are discussed in relation to the probable cause of death.