ANTIMICROBIAL FEEDS ARE ESSENTIAL FOR CONTROL OF FISH DISEASES AND FOR SUSTAINING PROFITABILITY IN THE AQUACULTURE SECTOR. UNFORTUNATELY, MULTIDRUG-RESISTANT (MDR) PLASMIDS HAVE BEEN REPORTED AMONG BACTERIAL STRAINS IN CATFISH FARMS IN THE UNITED STATES. THE POTENTIAL SPREAD OF THESE PLASMIDS COULD ADD CONSIDERABLE AND AVOIDABLE COSTS TO THE CATFISH INDUSTRY BY INCREASING THE FREQUENCY OF TREATMENT FAILURES. HOWEVER, FACTORS THAT FOSTER THE TRANSFER AND PERSISTENCE OF THESE PLASMIDS IN THE AQUATIC ENVIRONMENT REMAIN UNCLEAR AND UNINVESTIGATED. THE OBJECTIVE OF THE CURRENT PROPOSAL IS TO UNDERSTAND THE FATE, MOBILITY, AND DISSEMINATION OF THESE PLASMIDS IN THE AQUATIC ENVIRONMENT. CURTAILING THE SPREAD OF MDR-PLASMIDS REQUIRES A COMPREHENSIVE UNDERSTANDING OF WHEN, WHERE, AND HOW RESISTANCE WAS ACQUIRED, AND HOW PLASMIDS MOVE AMONG AND WITHIN ENVIRONMENTS. THE TWO SPECIFIC AIMS OF THIS PROPOSAL ARE TO: 1) EXAMINE THE TRANSMISSION DYNAMICS AND FATE OF MDR-PLASMIDS IN CATFISH MICROBIOTA.; 2) DETERMINE THE IMPACT OF ANTIMICROBIAL USE ON TRANSFER OF MDR-PLASMIDS.DATA GENERATED FROM THIS STUDY WILL PROVIDE A COMPREHENSIVE UNDERSTANDING OF THE FATE AND PREVALENCE OF MDR-PLASMIDS IN THE AQUACULTURE ENVIRONMENT, AND EFFECTS OF ANTIMICROBIAL USE ON THE PERSISTENCE OF THESE PLASMIDS IN CATFISH GUT MICROBIOME. THE PROPOSED QPCR ASSAY WOULD PROVIDE ADDITIONAL DIAGNOSTIC AND MANAGEMENT TOOLS FOR CATFISH PRODUCERS TO DETECT AND QUANTIFY THESE MDR-PLASMIDS IN THE AQUATIC ENVIRONMENT. A BETTER UNDERSTANDING OF THE TRANSMISSION OF MDR-PLASMIDS IS ESSENTIAL TO DEVELOP MANAGEMENT OPTIONS FOR REDUCING THE SPREAD OF AMR DETERMINANTS IN AQUACULTURE PONDS.