Nickel-induced histopathological alterations in the gill architecture of a tropical freshwater perch, Colisa fasciatus (Bloch & Schn.).

The effect of a sub-lethal concentration of 64 ppm (2.279 x 10(-4) mol l-1) of nickel sulphate (NiSO4.7H2O) on the gill of a freshwater tropical perch, Colisa fasciatus, was investigated after 96 h exposure. Prominent changes noticed were: hypertrophy of respiratory and mucous cells; separation of the epithelial layer from the pillar cell system; cauterization and sloughing; extensive necrosis of the epithelium; and hyperplasia leading to clubbing at the tip of the lamellae.