Specimens were taken from the kidneys of 777 fish of 10 species from Clear Lake, Iowa, in 1970 and 1971 to determine the carrier rate of Aeromonas salmonicida after a 1968 furunculosis epizootic that destroyed most of the yellow bass population. A. salmonicida was not detected in any fish examined. Serum from 5 of 46 yellow bass old enough to have been present during the 1968 epizootic contained agglutinins to A. salmonicida.