Flavobacterium psychrophilum, causative agent of bacterial coldwater disease (BCWD) and rainbow trout fry syndrome, is a top contributor to disease-associated losses in salmonid (Family Salmonidae) aquaculture around the world . In the USA, BCWD outbreaks are a perennial problem , including within aquaculture facilities and hatcheries of the North Central Region (NCR). Although a range of BCWD prevention and control measures are available, their efficacy is often inconsistent at best . One possible factor contributing to these inconsistencies is the intraspecific geno- and sero- diversity of F. psychrophilum that has become increasingly apparent in some regions of the USA and abroad. Unfortunately, most of the specific F. psychrophilum geno - and sero -variants responsible for losses in NCR trout and salmon farms have not been identified, a matter with likely implications for vaccine development and efficacy. To this end and as part of a larger s tudy aiming to enhance the health of US farmed fishes , efforts to isolate, identify, and characterize the predominating F. psychrophilum variants in NCR trout and salmon facilities are underway . Thus far, moribund salmonids from seven facilities in seven NCR states e.g., Michigan (MI), Ohio (OH), Iowa (IA), Wisconsin (WI), Minnesota (MN) , Missouri (MO) , and South Dakota (SD) have been collected, clinically examined, and bacteriologically analyzed. Examined fish (n=161 ) presented with a range of gross disease signs consistent with BCWD, including fin erosion, external ulceration, exophthalmia, v isceral hemorrhage and/or pallor , and splenic swelling and enlargement . C ultures for flavobacterial isolation (n=651 ) were prepared on FPM- A medium and inoculated with tissues f rom the gills, brain, kidney, spleen, and representative external lesions . As a result, 183 yellow- pigmented bacterial isolates were recovered, 121 of which were identified as F. psychrophilum via F. psychrophilum-specific endpoint PCR analyses . Overall , F. psychrophilum was detected in ~33% of the ex amined fish and from six of the seven facilities. As additional facilities in the NCR are being sampled, genotyping via multi locus sequence typing is underway. Likewise, molecular serotyping has been completed for a subset of the recovered F. psychrophilum isolates, revealing some interesting trends, including host species to serotype associations and that some facilities were affected by a single molecular serotype and others by two or more serotypes. After identifying the predominating F. psychrophilum variants in the sampled NCR facilities, lab and field -based experiments will test the protective efficacy of various autogenous bacterin preparation s, with the aim of producing efficacious, site-specific bacterins capable of enhancing fish health and productivity throughout the region. The findings from the study are expected to be of interest not only to fish health specialists but also to stakeholders in the aquaculture sector seeking effective strategies to mitigate the impacts of BCWD in the NCR.