Bacteria in blood and kidney of apparently healthy hatchery trout

Aseptic examination of blood and kidney material from three species of apparently healthy trout at two hatcheries showed that 12.5% of examined trout at one hatchery and 26.1% of trout at the other carried low numbers of bacteria. In addition, sera from these trout had agglutinins against some of the isolated bacteria and bacterial types found in trout were the same as those cultured from raceway water in which fish were raised. Although the presence of these bacteria does not constitute a disease state, the potential for an epizootic is present should trout be placed under stress conditions.