Simultaneous determination of antibiotic residues in edible tissue of farmed fish (

Aquaculture is one of the fastest-growing sectors in global food production, and its expansion has driven the adoption and consolidation of intensive and semi-intensive production methods, which can increase the risk of infectious diseases. The use of various antibacterial compounds for therapeutic purposes has become increasingly common. Monitoring the presence of antimicrobial substances in aquaculture is of the utmost importance to prevent antibiotic resistance and ensure food safety. A multi-residue method was applied to investigate the incidence and the concentration of antibiotic residues in fish flesh collected from Umbria and Marche aquaculture farms over the 4-year period 2020-2023. Due to its rapidity and reliability, this method allowed for the evaluation of 70 antimicrobial molecules in fish flesh and the verification of European Union legislation compliance. Overall, 102 samples were analyzed, and only three antibiotic substances were detected, namely, sulfadiazine, oxytetracycline, and trimethoprim, with a variable presence of positive samples and residue concentration through different seasons, with higher values in winter. The highest value of positive samples was registered in 2021, with 63.2%, followed by 62.2% in 2022 and 51.7% in 2020; 11.1% was registered in 2023. Non-compliant samples were recorded for sulfadiazine (only one at the concentration of 222 μg/kg) and trimethoprim (the concentration ranged from 10 μg/kg to 226 μg/kg). The results indicated that 53.9% of the samples contained residues of authorized substances, with a 6.9% above the respective maximum residue limits.