The Effects of Cadmium Exposure on Biochemical Indexes, Antioxidant Responses, Inflammation, and Anti‐Stress Responses of Juvenile GIFT Tilapia ( Oreochromis niloticus )

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This study investigated the effects of cadmium (Cd 2+ ) exposure on the biochemical indexes, antioxidant responses, non‐specific immune responses, inflammatory responses, anti‐stress responses, and related gene expression levels of juvenile GIFT tilapia ( Oreochromis niloticus ). Four groups of juveniles were cultured for 30 days in four aquaculture waters with different levels of Cd 2+ concentrations (0, 0.2, 0.4, and 0.6 mg/L). Key findings include: In comparison to the control group (0 mg/L Cd 2+ ), cadmium stress significantly impacted the liver and serum biochemical indices of juvenile tilapia ( p < 0.05). The activities of catalase (CAT), superoxide dismutase (SOD), and total antioxidant capacity (T‐AOC) in the gills, liver, and serum were significantly decreased ( p < 0.05) and the contents of malondialdehyde (MDA) showed the opposite trend. The expression levels of interleukin‐10 (IL‐10), sonic hedgehog (SHH), and cytochrome oxidase 1A (CYP1A) were significantly down‐regulated ( p < 0.05) and the expression levels of interleukin‐1β (IL‐1β), tumor necrosis factor α (TNFα), interferon γ (IFNγ), interleukin‐6 (IL‐6), interleukin‐8 (IL‐8), transforming growth factor β1 (TGF‐β1), metallothionein (MT), and heat shock protein 70 (HSP70) in the liver were significantly up‐regulated ( p < 0.05). In conclusion, the concentration of cadmium in aquaculture water exceeded 0.2 mg/L, and the biochemical indexes, antioxidant responses, non‐specific immune responses, inflammatory responses, and anti‐stress responses of juvenile GIFT tilapia were markedly altered. These findings highlight that even sub‐lethal Cd 2+ concentrations (≥ 0.2 mg/L) pose substantial risks to the physiological health and survival of juvenile tilapia.