Pathology of lindane poisoning and of hypoxia in the brown trout, <i>Salmo trutta</i> L.

Abstract

A comparative study of the signs of lindane poisoning and of hypoxia in trout, Salmo trutta L., showed that the symptoms of both causes of death are similar. The rapid fading of gill colour within 2 h of death is characteristic of both treatments and distinguishes these from other causes of death. Vascular congestion and cellular damage of the liver is common to both treatments. The causes of death may be distinguished by the behaviour of the fish before death and by study of their effects on the gills. Hypoxic fish showed increased ventilatory activity, but other activity decreased. Exposure to lethal levels of lindane caused hyperactivity, convulsions, ataxia and intermittent paralysis. Although gill damage in both cases was slight it was distinctive. Lindane caused disarray of the secondary lamellae, and exposure to low dissolved oxygen levels caused breaks in the lamellar epithelium. This was only clearly visible under electron microscopical examination.