Effects of sublethal arsenic on Clarias gariepinus juveniles’ behavior, tissue damage, and oxidative stress response

African catfish is the single most cultured fish in Nigeria, and most culture systems depend on surface water abstraction. This has meant continuous exposure to emerging toxicants, including heavy metals. Arsenic is one of the widespread heavy metals present in the aquatic environment posing a threat to humans, animals, and fishes. To assess the effects of sublethal arsenic exposure to juvenile stage Clarias gariepinus juvenile, this study evaluated different sublethal doses of arsenic (۲۰, ۴۰, ۶۰ mg/L) based on the estimated lethal (۹۶ hrs-LC۵۰) of ۷۷.۱mg/L. Behavioral responses, such as swimming activities, body weakness, surfacing, lethargy, loss of mucus, state of inactivity, and jumping, were observed. To keep track of the effect on tissue damage and oxidative stress response, we conducted enzymes activities assays to measure the activity of ALP, AST, ALT, CAT, and SOD. Results indicated that subacute exposure (۹۶ hrs) to sublethal arsenic strongly distorted the normal behavior of African catfish. In which fish group exposed to ۲۰, ۴۰, and ۶۰mg/l showed inactivity, increased mucus production, lethargy, and frequent surfacing. While exposure to sublethal arsenic showed induced no significant difference in hepatic enzymes activities (ALP and ALT), these exposures were noticeably (p<۰.۰۵) considering AST. Again, no significant differences in the antioxidant enzyme activities (CAT and SOD) in all fish groups exposed to sublethal arsenic. Overall, while there were no signs of oxidative stress, the significance reported in AST gives the reason to suspect sublethal arsenic concentration impacts African catfish tissue integrity. It is important to note that the behavioral-induced response may pose a risk to aquaculture stocks, as this may ultimately impact fish performance and fitness to aquaculture conditions.

Keywords:

Arsenic , Toxicity , Fish , Mortality , Oxidative stress