FLAVOBACTERIUM PSYCHROPHILUM (FP), CAUSATIVE AGENT OF BACTERIAL COLDWATER DISEASE (BCWD), IS A TOP DISEASE IMPEDIMENT FOR US-FARMED TROUT AND SALMON. THIS BACTERIUM IS TRANSMITTED HORIZONTALLY AND VERTICALLY, MAKING PREVENTION AND CONTROL DIFFICULT. MOREOVER, FEW FDA-APPROVED TREATMENT OPTIONS EXIST, AND US-VACCINES ARE CURRENTLY UNAVAILABLE. OUR RECENT USDA-FUNDED RESEARCH UNCOVERED SUBSTANTIAL US FP DIVERSITY, REVEALED THE PREDOMINATING FP STRAINS CAUSING OUTBREAKS, AND HIGHLIGHTED THAT FP TRANSMISSION FROM PARENTS TO OFFSPRING IS BEHIND MANY OUTBREAKS, A CONCERN GIVEN POOR EFFECTIVENESS OF EGG DISINFECTION PROTOCOLS. OUR OVERARCHING GOAL IS TO ARM AQUACULTURISTS WITH IMMEDIATELY DEPLOYABLE METHODS FOR REDUCING FP-INDUCED LOSSES BY HALTING PARENT-OFFSPRING TRANSMISSION VIA: 1) IDENTIFYING PREDOMINATING FP SEROTYPES ASSOCIATED WITH ECONOMIC LOSSES IN US-AQUACULTURE; 2) DEVELOPING A RAPID ASSAY FOR USE "PONDSIDE" BY FARMERS, THEREBY IDENTIFYING FP-FREE BROODSTOCK AND EGGS; 3) OPTIMIZING A NOVEL EGG DISINFECTION PROTOCOL THAT IS EFFECTIVE AGAINST ALL US-PREDOMINATING FP VARIANTS; 4) MODELING GENERATED FINDINGS AND INCORPORATING THEM INTO ENHANCED BEST MANAGEMENT PRACTICES (BMP) TO CONTROL BCWD; AND 5) DISSEMINATING ENHANCED BMPS AND TRAINING AQUACULTURISTS TO PERFORM "PONDSIDE" TESTING VIA WORKSHOPS AND WEBINARS. THIS RESEARCH WILL IMPROVE FARMED TROUT/SALMON PRODUCTION IN SHORT-TERM BY ARMING US AQUACULTURITSTS WITH TOOLS AND TRAINING TO PREVENT FP EGG-ASSOCIATED TRANSMISSION. PRODUCTION/PROFITABILITY WILL IMPROVE MEDIUM-TERM VIA REDUCED ANTIBIOTIC USE, IMPROVED FP BMPS, AND BY GUIDING A LONG-TERM OBJECTIVE OF VACCINE DEVELOPMENT. THIS PROPOSAL ADDRESSES "CRITICAL DISEASE ISSUES IMPACTING COMMERCIAL AQUACULTURE SPECIES, " GOALS 2&AMP;4 USDA-NIFA SPECIAL RESEARCH GRANTS PROGRAM, 2018-2022 USDA STRATEGIC GOALS, AND THE ANIMAL HEALTH AND PRODUCTION AFRI PRIORITY AREA (2008 FARM BILL).