AQUACULTURE IS THE FASTEST GROWING ANIMAL FOOD SECTOR IN THE GLOBAL MARKETPLACE. HOWEVER, DISEASE OUTBREAKS ARE A MAJOR HURDLE FOR THE GROWTH OF THE INDUSTRY. IN ORDER TO PREVENT AND/OR TREAT FISH DISEASES, THE INDUSTRY RELIES ON A SIGNIFICANT ARSENAL OF FISH VACCINES AS WELL AS CHEMO- AND NON-CHEMOTHERAPEUTIC OPTIONS, INCLUDING PROBIOTICS. VACCINES ARE NOT ALWAYS COST EFFECTIVE FOR A NUMBER OF AQUACULTURE SPECIES, OR THEY SIMPLY DO NOT EXIST FOR A GROWING NUMBER OF FISH PATHOGENS, ESPECIALLY PARASITES. CHEMOTHERAPEUTICS (E.G., ANTIBIOTICS, FORMALDEHYDE, MALACHITE GREEN) ARE OFTEN EXPENSIVE AND HAVE A SIGNIFICANT NEGATIVE ECOLOGICAL IMPACT ON THE AQUATIC ENVIRONMENT AND ITS SURROUNDINGS. THUS THERE IS AN URGENT NEED TO FIND ALTERNATIVE COST-EFFECTIVE, AND ECO-FRIENDLY THERAPEUTIC STRATEGIES FOR THE PREVENTION AND TREATMENT OF FISH DISEASES. CONSEQUENTLY, THE USE OF PROBIOTICS HAS EMERGED AS A POWERFUL THERAPEUTIC ALTERNATIVE IN THE AQUACULTURE INDUSTRY, ALTHOUGH THEY COMPRISE A VERY MINOR PART, THUS FAR, OF THE THERAPEUTICS CURRENTLY BEING USED BY THE INDUSTRY. PROBIOTICS ARE MICROBES THAT WHEN DELIVERED TO AN ANIMAL SPECIES, IN THIS CASE FISH, THEY ARE KNOWN TO IMPROVE A WIDE RANGE OF PHYSIOLOGIC PROCESSES, INCLUDING GROWTH, DIGESTION, GUT INFLAMMATION, IMMUNITY, PATHOGEN RESISTANCE, AMONG OTHERS. THIS PROJECT PROPOSES FOR THE FIRST TIME IN FISH THE IDENTIFICATION AND CHARACTERIZATION OF RATIONALLY SELECTED FISH IMMUNOBIOTICS. THE TERM IMMUNOBIOTIC (IMB) WAS COINED IN 2003, AND IT REFERS TO PROBIOTICS THAT ARE SPECIFICALLY SELECTED TO ENHANCE HEALTH THROUGH ACTIVATION OR POTENTIATION OF THE MUCOSAL IMMUNE SYSTEM. RECENT FINDINGS IN OUR LABORATORY HAVE POINTED TO THE EXISTENCE OF FISH IMMUNOBIOTICS, THAT LIVE IN THE FISH MUCOSAL AREAS, AND HAVE THE CAPACITY TO ENHANCE THE IMMUNE SYSTEM AT SUCH MUCOSAL SITES. THIS IS IMPORTANT BECAUSE THE OVERWHELMING MAJORITY OF FISH PATHOGENS INFECT FISH THROUGH SUCH MUCOSAL AREAS, INCLUDING THE SKIN AND GILLS OF THE FISH. THUS, THE POTENTIATION OF THE IMMUNE SYSTEM IN SUCH AREAS BY THESE IMBS MAY LEAD TO BETTER RESISTANCE OF FISH TO DISEASES. OUR FINDINGS THUS FAR INDICATE THAT THESE IMMUNOBIOTICS HAVE THE CAPACITY TO PROTECT FISH FROM ICH, AN IMPORTANT PARASITE THE AFFECTS MANY FARMED FISH SPECIES. IN THIS PROJECT WE WILL IDENTIFY AND SELECT A NUMBER OF FISH IMBS WITH THE GOAL TO PROTECT FISH FROM PARASITIC, BACTERIAL AND VIRAL PATHOGENS. THUS, THE RESULTS FROM THIS PROJECT WILL BE SIGNIFICANT AND INNOVATIVE FROM AN APPLIED PERSPECTIVE, BECAUSE THEY WILL PAVE THE WAY FOR THE DEVELOPMENT OF A NOVEL CLASS OF THERAPEUTICS FOR FISH: IMBS THAT SPECIFICALLY PROMOTE MUCOSAL HEALTH BY INDUCING MUCOSAL IMMUNE AND PROTECTIVE RESPONSES AGAINST FISH PATHOGENS. THEREFORE, THIS PROJECT WILL BENEFIT IN THE LONGTERM THE US AQUACULTURE INDUSTRY BY DECREASING PATHOGEN-RELATED FISH MORTALITIES IN THE FISH FARMING INDUSTRY. IN TURN, THIS WILL MAKE US AQUACULTURE A MORE ROBUST AND ECONOMICALLY VIABLE INDUSTRY.