Architectural Changes in the Gill Morphology of the Freshwater Fish, Esomus danricus as Potential Biomarkers of Copper Toxicity Using Automated Video Tracking System

Biomarker responses at the histological level to xenobiotics are gaining a priority research interest. The 96h LC50 of copper sulfate to Esomus danricus is found to be 5.5 mg/L and its toxic effects on fish gills are critically examined in situ. Gills (pair III) of fish exposed to 5.5 mg/L and 0.55 mg/L of copper sulfate and control without toxicant were placed in normal saline medium and, after rinsing, placed on a glass slide and observed under a Polyvar, Reichert-Jung light microscope attached to Ethovision-version 2.3 (Noldus Information Technology, Netherlands) through a Sony CCD IRIS camera (Model No: SSC-M370CE). Damage to secondary gill lamellae with loss of shape, necrosis, clubbing and fusion, shaft breakage, atrophy, curvature of tips, thick mucous sheathing and degeneration of rakers are observed in fish exposed to 5.5 mg/L of copper sulfate. Primary and secondary gill lamellae are affected with loss of original shape, loss of alignment in rakers with hyper secretion of mucous in fish exposed ...