Changes in the bacterial composition of water in a carp rearing tank

The bacteria from an 800-l carp rearing tank were isolated on five different media during a 45-day experimental period. Total viable counts and the variety of groups of bacteria detected in the water increased after the carp were stocked. The Vibrio-Aeromonas group and Bacteroides type A, which were major components in the intestinal tracts of carp, increased after fish were introduced, and decreased after fish were removed.