Biological factors impinging upon control of external protozoan fish parasites

Abstract

Various protozoans commonly occur on the external surfaces of fishes under aquaculture conditions. Their pathologic impact is dependent upon mode of attachment and feeding method, numbers of protozoans, and host condition. Economic impact is dependent upon population dynamics, pathologic potential, production expectation, and control costs. These factors complicate control decisions since prevention of all protozoan occurrence on the fish host is not usually cost-effective.

This review describes various biologic features that contribute to a protozoan’s disease causing potential and examines some of the opportunities fish health managers have for control.