Haemato-biochemical changes in epizooticulcerative syndrome (EUS) infected striped murrel (Channa striata) cultured in inland saline water

Epizootic ulcerative syndrome (EUS) causes infection in a wide range of fish species, often leading to significant mortality worldwide. Among the susceptible hosts, snakeheads are reported to be particularly vulnerable. A 120-day investigation was undertaken to examine the impact of salinity on Channa striata cultured in inland saline water. Twenty-four circular fibre-reinforced plastic (FRP) tanks ( 400 l capacity) were filled with water adjusted to eight salinity levels viz., 0 ppt (control) and treatments T1-T7 (0, 2, 4, 6, 8, 10, 12 and 14 ppt) each in triplicates, following a completely randomised design. Each tank was stocked with 24 juveniles (mean weight: 8±2.09 g) and fed with Growel feed containing 42% crude protein twice daily (09.00 hrs and 17.00 hrs). Mortalities were noticed in fish reared at 0, 12 and 14 ppt salinity levels, around the 90th day after introduction into the experimental tanks. Affected fish were found lethargic, swimming at water surface, pale and isolated, having fungal growth and haemorrhages with ulcerated skin. Polymerase chain reaction (PCR) confirmed the presence of EUS in affected fish. Both biochemical and haematological parameters altered in the affected fish. The findings suggest that moderate salinity levels in inland saline water may help prevent the occurrence of EUS and could be effectively employed for sustainable aquaculture of C. striata. Keywords: Aquaculture production, Aetiology, Aphanomyces invadans, Inland saline groundwater, Pathogens