Robert E. LEVIN
Twenty three strains of Shewanella were isolated from an inland fresh water tilapia fish farm and identified on the basis of biochemical tests. The mole% G+C for these isolates ranged from 45.5% to 48.9%. At one sampling of the fish tank water, 70% of the total aerobic CFU con-sisted of Shewanella. Random amplified polymorphic DNA (RAPD) analysis performed sepa-rately with three decamer primers designated LMPB4, LMPB1, and LMHLWL74 yielded 4, 5, and 4 different profile types respectively. Composite profiles derived from the 3 RAPD primers yielded 7 composite banding profiles from the 23 Shewanella isolates. The results of this study indicate that a heterogeneous population of Shewanella strains was frequently present in the fish tank water, and that on occasion, for as yet unknown reasons, a single clone may dominate the total aerobic bacterial population of the fish tank water.
