Ultrastructural changes in fin epithelium of Channa punctatus (Bloch) exposed to mercuric chloride: sem study.

Fish skin is in direct contact with water and forms the first line of defense against pathogens and toxicants present in the surrounding water. The effect of mercuric chloride (HgCl2) on surface architecture of the epidermis of caudal fin of an air breathing fish, Channa punctatus was examined by scanning electron microscopy (SEM) and revealed the presence of microridges that formed intricate, maze-like patterns. The exposed fish showed significant alterations including disorganization of microridge pattern and increase in number as well as enlargement of mucus cell openings. These findings exhibited concentration- and time- dependent alterations in fin epithelium. Data demonstrated that fin epithelium of fish may be successfully employed as a bioindicator of water pollution.