Integrated multi-omics analysis reveals mechanistic insights into the combined toxicity of copper and tebuconazole at environmentally relevant concentrations in Opsariichthys bidens

Freshwater organisms are routinely exposed to complex mixtures of pollutants, yet current risk assessments largely fail to account for their combined effects. Here, a comprehensive approach was employed to elucidate the toxicological responses in the livers of hook snout carps ( Opsariichthys bidens ) following co-exposure to the heavy metal copper (Cu) and the pesticide tebuconazole (Teb). Our findings demonstrated that simultaneous exposure to Cu and Teb elicited a pronounced synergistic toxicity in O. bidens . The observed synergy stemmed from the distinct modes of action of the two pollutants: Cu induced oxidative stress via the Fenton reaction, while Teb disrupted cytochrome P450–mediated metabolism. Both individual and combined exposures elicited a spectrum of adverse effects, including histopathological alterations, oxidative stress, apoptosis, inflammation, impaired detoxification, endocrine disruption, and disturbances in amino acid and glycolipid metabolism, with the mixture (Mix) producing markedly more severe impairments. Their interaction initiated a self-reinforcing cycle, beginning with the collapse of the antioxidant system, cascading into profound disruption of the TCA cycle and glycolipid metabolism, and ultimately culminating in an energy crisis accompanied by amplified apoptosis. These findings established a mechanistic framework for evaluating the combined ecological risks of organic and inorganic pollutants.