Recirculating 2271-liter culture systems were designed and evaluated as potential fish production units. System components include a culture tank, sedimentation basin, and a biological filter. Three different biological filter types were compared: a commercially available plastic filter media, a rotating biodisc filter, and a submerged gravel filter. Each duplicated system was stocked with 5 cm fingerling channel catfish, lctalurus punctatus, which were fed daily. The experiment continued until maximum loading capacities were attained. In the 155 day growing period, the greatest standing crop attained was 41.2 kg using the rotating biodisc filter. Excepting one replication which exhibited 100 percent mortality due to an aerator failure, survival rate was 95 percent or greater, with feed conversions ranging from 1.27 to 1.62.
