Mitigation of benzo[a]pyrene-induced toxicity in Nile tilapia using Phoenix dactylifera seed biochar

Abstract Benzo[a]pyrene (BaP), a common polycyclic aromatic hydrocarbon, poses an increasing threat to aquaculture systems because of its detrimental effects on fish health-related physiological traits. The current study investigated the prospective use of Phoenix dactylifera seed biochar (PDB) to reduce the various hazardous effects triggered by BaP toxicity in Nile tilapia ( Oreochromis niloticus ). For 30 days, fish were randomly assigned to five groups: control, acetone, PDB, BaP, and PDB+BaP. The outcomes clarified that BaP exposure caused a marked reduction in fish survival and induced hematological impairments. In addition, a suppression of immuno-antioxidant responses and acetylcholinesterase activity, along with an elevation of malondialdehyde, cortisol, and glucose concentrations, were observed following BaP exposure. Moreover, the BaP group revealed hepato-renal dysfunctions and histopathological changes in gill, liver, brain, and muscular tissues as well as downregulation of immune-related genes (interferon-alpha and interleukin-10). Furthermore, upregulation of the apoptotic gene ( caspase−3 ), higher residual levels, and a lower survival rate following an Aeromonas hydrophila challenge were found in the BaP-exposed fish. Co-treatment with PDB ameliorated most of the alterations induced by BaP, which was accompanied by enhanced survival, improved tissue architecture, and decreased BaP residues. Following the A. hydrophila challenge, Kaplan–Meier analysis showed a noticeable numerical improvement in the cumulative survival probability of the PDB+BaP group compared to the BaP-exposed group, although the difference was not statistically significant. In conclusion, the outputs of this investigation highlight the practical value of PDB as a promising, low-cost, adsorbent-based strategy for protecting Nile tilapia from BaP contamination, thereby supporting healthier and more resilient aquaculture production systems.