Behavioral and histo-pathological indices of striped catfish (Pangasionodon hypophthalmus) exposed to different salinities

Abstract

Salinity intrusion due to climate changes in the coastal area is substantially jeopardized for sustainable aquaculture. This study was focused on behavioral and histo-pathological changes (gills, liver and kidney) of striped catfish (Pangasionodon hypopththalmas) exposed to four salinities (0, 4, 8 and 12 ppt), each with three replications for 56 days. Both behavioral and histological analyses were carried out for durations of 7, 14, 28 and 56 days of exposure. Mild to moderate behavioral abnormalities such as rate of swimming, food intake, gill motion and convulsions were observed in 8 ppt, but pronounced alterations were detected at higher salinity (12 ppt), increasing with longer exposures. Similarly, mild to moderate histological anomalies in gills (hypertrophy of the chloride cell, telangiectasia at the tips of secondary lamellae, epithelial necrosis, fusion of some secondary lamellae and lifting of the lamellar epithelium), liver (vacuolation, blood congestion, melanomacrophage centers, patchy degeneration, necrosis and hypertrophy nucleus) and kidney (degeneration of renal tubule, enlarged Bowman's capsule, increased space in between glomerulus center, melanomacrophage centers, vacuolation and necrotic cell in the hematopoetic tissue) were detected in 8 ppt but pronounced alterations were detected at higher salinity (12 ppt) with increasing the days of exposure. This preliminary study revealed more profound responses to higher salinity exposure in the striped catfish, and this species could serve as a model bio-indicator in costal aquaculture.