ABSTRACT
Cultured finfish and shellfish accounted for over 25 percent of world aquatic animal production, or close to 100 million metric tons, in 1996 (FAO 1998). As fish increase as a protein source throughout the world and natural fish stocks decline, culture practices will intensify and environmen tal conditions in culture systems will deteriorate. Deterioration of the cul ture environment will lead to more problems with disease, not only because of the increased number of animals in a limited and confined space, but also because of the influence of poor environmental conditions such as water quality on the fish immune system. The result will be an increased and con tinued negative effect of disease on production.
