Aquaculture is the production of fish and shellfish for market under controlled or semi-controlled conditions. For commercial success, an aquaculture operation must maintain fish at densities that greatly exceed those normally found in nature. Under these conditions, fish must not only survive, but grow rapidly. Regardless of the culture system used (e.g., ponds, raceways, reuse systems, cages) it is imperative that the culturist maintain an environment conducive to good fish health.
A wide variety of parasites and pathogens can and do infect fish. Most disease agents are naturally present in low numbers and normally do not cause problems. The natural defense mechanisms of fish (i.e. an undamaged skin, mucus covering the skin, and various components of the immune system) keep them in check. However, when fish already crowded in culture operations are further stressed (e.g., by low dissolved oxygen, nutritionally inadequate feeds, excessive handling) their natural disease defense systems (immunity) may be weakened and the ability of the fish to protect itself against infectious diseases may be reduced. Disease induced catastrophic mortalities are frequently the result of, and response to, a stressful experience. Most disease problems can be avoided with proper management.
[Information for this web site was modified from that contained in:
Bowser, P.R. and Buttner J.K. 1991. General Fish Health Management. Northeastern Regional Aquaculture Center/USDA Bulletin 111-1991. Used with permission]