** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE USE OF ANTIBIOTICS IN ANIMAL AGRICULTURE IS ONE OF THE DRIVERS OF ANTIMICROBIAL RESISTANCE (AMR). WHILE MAJORITY OF RESEARCH HAS BEEN ON BACTERIA PRESENT IN LAND ANIMALS, VERY LIMITED INFORMATION IS AVAILABLE ABOUT AMR IN AQUACULTURE. THERE ARE THREE ANTIMICROBIALS APPROVED BY THE FDA FOR USE IN AQUACULTURE: OXYTETRACYCLINE HYDROCHLORIDE, SULFADIMETHOXINE AND ORMETOPRIM, AND FLORFENICOL. THESE THREE DRUGS ARE EFFECTIVE FOR TREATING BOTH WARM-WATER FISH DISEASES AND COLD-WATER FISH INFECTIONS. HOWEVER, THERE IS A CRITICAL KNOWLEDGE GAP THAT NEEDS TO BE BRIDGED FOR ENSURE THE SUSTAINABLE USE OF ANTIBIOTICS, THAT IS HOW WATER TEMPERATURES IMPACT THE FORMATION OF AMR IN FISH AND IN AQUACULTURE ENVIRONMENT WHEN THESE ANTIBIOTICS ARE APPLIED AT DIFFERENT DISEASE BREAK-OUT TEMPERATURES. TO ANSWER THIS QUESTION, IN VIVO ANIMAL TREATMENT EXPERIMENT WILL BE CONDUCTED BY UC DAVIS AND AUBURN UNIVERSITY. THE TRIAL AT UCD WILL USE WELL WATER WHILE THE TRIAL AT AUBURN WILL USE SURFACE WATER. THE ABUNDANCE, DIVERSITY, AND CHANGES OF AMR BACTERIA AND ANTIMICROBIAL RESISTANT GENES (ARGS) PRESENT IN FISH AND REARING WATER BEFORE AND AFTER ANTIBIOTIC TREATMENTS WILL BE INVESTIGATED USING CULTURE-BASED AND METAGENOMICS APPROACHES. AN ANTIBIOTIC USAGE GUIDELINE WILL BE DEVELOPED AT THE END OF THE EXPERIMENT AND WILL BE DISSEMINATED TO FARMERS, VETERINARIANS, AND THE GENERAL PUBLIC VIA MULTIPLE EDUCATION AND EXTENSION PLATFORMS.