Probiotics improve water quality by decreasing concentrations of ammonia and nitrite and inhibit pathogens by producing antibacterial substances, by competitive exclusion, and by stimulating the host immune system. We have collected isolates worldwide and by using are high-throughput screening techniques we have tested them for growth at different pH, salinities and temperatures and for inhibition against pathogens that are pervasive in aquaculture and for their ability to reduce ammonia, nitrite, nitrate and phosphorus. We selected a handful to demonstrate how the testing we have done can lead to better probiotic combinations. For example, RA203 and 9H6 can grow at 15°C, RT, and 30°C and inhibit all but one pathogen tested. (Table 1 and 2). Isolate 6G11 has a stronger inhibition than the rest against our target pathogens.
RA19 or RA54 could be good candidates to reduce ammonia and phosphorus. RA805 a new isolate that needs more testing has shown to be the best at reducing phosphorus (Chart 1) . Also, t he isolates are tested for enzyme activity: amylase, protease, cellulose, citrase and numerous others. The only enzyme tested not produced by RA203 and 9H6 is amylase. Therefore, we would choose another isolate to add to fulfill this need. A combination of RA203 , 9H6 and 6G11 and possibly RA805 would make a probiotic combination good for use in different environments.