Physiological and histological study of the toxicity and biocompatibility of graphene oxide and GO–PVA nanocomposite hydrogels in the treatment of metal-contaminated water for Oreochromis niloticus aquaculture

Abstract Heavy metals in aquaculture water from industrial effluent, mining, and agricultural runoff pose risks to ecosystems and human health. Graphene oxide (GO) effectively adsorbs heavy metal ions but can be toxic to fish. A composite of PVA hydrogel with GO enhances water quality maintenance in aquaculture. While PVA-GO hydrogel's adsorption capacity has been studied, its environmental and toxicological impacts are unclear. This study examines the biocompatibility of low-concentration PVA-GO hydrogel composites for water treatment, comparing untreated, metal-contaminated, and treated water samples in Oreochromis niloticus aquaculture. The synthesis of GO and PVA-GO hydrogel was analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and FTIR spectra. The results indicated that heavy metal-contaminated water caused significant anemia and altered plasma biochemistry, while the biomarkers in treated groups returned to levels similar to the control. Additionally, GO and PVA-GO hydrogels exhibited intestinal antibacterial activity. This research suggests that combining GO with PVA hydrogel reduces toxicity to fish, improves heavy metal removal, and enhances their health in aquaculture environments.