Comparative assessment of haematological and serum biochemical alterations in silver carp (Hypophthalmichthys molitrix) exposed to sublethal concentrations of arsenic, cadmium and cobalt

The present study investigated the comparative effects of arsenic (As), cadmium (Cd), and cobalt (Co) on the haematological and serum biochemical profiles of silver carp ( Hypophthalmichthys molitrix ). A total of 240 silver carp (average weight: 8.00 ± 0.79 g) were randomly distributed into four experimental groups: control, arsenic (0.06 mg/L), cadmium (0.06 mg/L), and cobalt (0.06 mg/L) treatments, with three replicates each for a period of 60 days. The results revealed a significant increase in total white blood cell (WBC) counts in all metal-exposed groups compared with the control ( p < 0.05). In contrast, red blood cell (RBC) count, haemoglobin (Hb), haematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), and mean corpuscular haemoglobin concentration (MCHC) showed marked reductions following exposure. Furthermore, significant alterations in serum biochemical parameters were observed, suggesting physiological disturbances and possible alternation in metabolic processes associated with heavy metal stress. Cadmium caused the greatest decrease in total protein and albumin levels, showing that it affected protein metabolism more severely than the other metals. A reduction in globulin levels suggested a weaker immune response, while increased glucose and cortisol levels indicated stress in the fish. Among the metals tested, cadmium induced comparatively greater alterations in haematological and biochemical parameters, followed by cobalt and arsenic at the tested concentration. Overall, long-term exposure to these heavy metals caused significant changes in the haematological and serum biochemical profile of silver carp.