Abstract

Static bioassay was conducted to determine the 96h median lethal level (LC₅₀) of copper sulphate on Heterobranchus biborsalis fingerlings (5.84 ± 0.5 g and length of 6.00 ± 1.0 cm respectively) and to describe the histological changes in the gill, liver, kidney, intestine and heart. LC₅₀ of H. bidorsalis fingerlings was determined graphically as 0.39 ppt. Fish displayed the following behaviors jumping out of the tank (at higher concentration), erratic swimming, discoloration, hyperventilation, irregular operculum and tail beat frequencies and loss reflex during 96 h exposure. Histological examination revealed that gill architecture was destroyed and erosion of gill lamellae, raker and edema. The liver showed distorted liver cells, severe vacuolation of the hepatocytes, fibrosis, coagulative necrosis in the liver parenchyma and round cell infiltration, in the hepatic parenchyma. The kidney showed enlarged globular lumen and damage of proximal tubules, vacuolization and lesions at the highest concentration of copper sulphate. Also the intestine revealed severe degeneration and necrotic changes in the intestinal mucosa cells and submucosa. Lastly the heart showed degeneration of cardiac muscle fiber, atrophy of the cardiac muscle fiber and edema of the atro-ventricular funnel near the entrance of the ventricle on exposure to high concentrations of copper sulphate.

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