Temperature modulates gut microbiome disruption and resistome enrichment in oxytetracycline-treated channel catfish ( <i>Ictalurus punctatus</i> )

This study reveals that water temperature critically shapes how antibiotics affect the gut microbiome and antimicrobial resistance in channel catfish. Metagenomic sequencing results showed that oxytetracycline (OTC) treatment caused minimal disruption of the microbiome at 20°C, but induced significant community shifts and enrichment of antimicrobial resistance genes (ARGs) at 25°C and 30°C. Higher temperatures reduced microbial resilience, consolidating ARGs within key bacterial genera such as <i>Klebsiella</i> and <i>Enterococcus</i>. Importantly, OTC-induced microbiome changes and resistance persisted through the withdrawal period. These findings highlight temperature as a major driver of antibiotic impact in aquaculture, emphasizing the prudent use of antibiotics at different disease breakout temperatures.