Sensitivity of branchial mucous to crude oil toxicity in a freshwater fish,Colisa fasciatus

Abstract

In the maintenance of respiratory activity of the gills in fishes, mucus secretion is known to have an important function. Crude oils and their fractions enter the fish tissue by positive transfer via the gills thus the mucus cells of gill epithelia act as an obvious site of pathogenic interactions between the fish and the environment. Mucous cell hyperplasia is a general phenomenon associated with crude oil toxicity. Even though a large quantity of crude oil pollutes the freshwater environment annually, literatures on the pathogenic effect of oil pollutants on the branchial mucous cells of fishes are limited to the marine and estuarine species. This investigation has been undertaken to provide a better understanding of the pathogenic effects of crude oil on the branchial mucous of a freshwater fish, Colisa fasciatus. The toxicity assessment is based on the histochemical observations of mucous cells present in the epithelia of gill rakers and filaments.