Generation and dissemination of data for safe and effective therapeutic applications for minor use in major species or for use in minor species is a priority of the FDA/CVM's Office of Minor Use and Minor Species Animal Drug Development (OMUMS). This project addresses the need to increase the availability of therapeutics to sectors of the aquaculture industry not covered by the original approval. The lack of approved drugs for marine finfish producers is threatening the growth and long-term viability of these collective industries and the security of our food supply. Although some new aquaculture drugs have been added to the collective finfish “medicine chest” in the past 10-15 years, the total number of FDA-approved drugs for aquatic animals is still very limited. Researchers within the Cornell University Aquatic Animal Health Program and USFWS Aquatic Animal Drug Approval Partnership (AADAP) program are proposing to continue a collaboration to conduct studies to increase the number of safe and effective drugs that can be used to benefit the U.S. aquaculture community. Trials will be conducted with Florfenicol (AQUAFLOR®), which is used to treat specified diseases of fish. Cornell University’s Aquatic Animal Health Program brings a long history of conducting research on fish therapeutants and was funded by NIFA during the last two years. This grant application proposes tasks that will be completed in partnership with the team of researchers, pathologists, statisticians, and quality assurance personnel at both the Cornell University College of Veterinary Medicine and AADAP. This study will evaluate the safety of AQUAFLOR® to saltwater-reared marine finfish administered in feed to marine finfish species at 0× (0 mg), 1× (15 mg), 3× (45 mg), or 5× (75 mg) the maximum proposed therapeutic dose of 15 mg florfenicol/kg fish/day for 20 consecutive days (2× the proposed therapeutic treatment duration of 10 consecutive days). The target animal safety study of AQUAFLOR® will be conducted with juvenile marine finfish species. The results of these safety studies, if accepted by FDA/CVM, will be used to complete the TAS technical section data requirements for marine finfish and support a New Animal Drug Application to FDA/CVM to approve the use of AQUAFLOR® for the control of mortality in seawater-reared finfish due to yellowmouth associated with Tenacibaculum maritimum.