Effects of Sublethal Cadmium Exposure on Hemato-Biochemical Parameters and Tissue Accumulation in Wallagu attu

This research investigates the effects of sublethal cadmium (Cd) exposure on Wallagu attu, focusing on physiological impacts. Seventy fish, averaging 144.8±24 g, were divided into control and Cd exposed groups (35 fish each) in 130 L fiberglass tanks. The Cd-treated group was exposed to one-third of the lethal concentration (LC₅₀) for 1, 20, and 40 days. The study assessed metal accumulation and hemato-biochemical responses post-exposure. Results showed a significant increase in metal accumulation in Cd-exposed fish, with the highest Cd levels in the kidneys, followed by the gills and intestines. Catalase and Superoxide Dismutase activities significantly decreased in the Cd-treated group, particularly on day 40. On days 20 and 40, Cd-exposed fish exhibited significant reductions in red blood cells, hemoglobin, hematocrit, and total protein. Conversely, glucose and cortisol levels increased significantly with prolonged Cd exposure. No mortality was recorded up to day 20, but by day 40, the mortality rate reached 11.43%. This study underscores the significance of managing sublethal Cd-induced stress to mitigate heavy metal impacts and protect aquatic ecosystems.