Diseases in Aquaculture

From the time man started to culture fish, fish diseases changed from being an interesting phenomenon to an important socio-economic problem. Infectious disease is considered to be the industry's single most important cause of mass mortalities and economic losses. Therefore, effective disease control is consequently regarded as the single most important cost factor after feed. A range of infectious organisms including bacteria, viruses, protozoan and metazoan parasites, and fungi causes disease in fish.

Most economic losses related to diseases are caused by mortality and reduced growth. Estimates from various organisations have indicated that approximately 50% of all fish and shrimp put into cages and ponds are lost due to disease before they reach market size. The actual economic losses in the aquaculture industry worldwide are estimated to be in excess of US$9 billion per year, which is roughly 13% of the world's farmed fish and shellfish value. The traditional animal species of agricultural importance, cattle, sheep, pigs, poultry, etc., tend to be now globally distributed; in principle, the major diseases of these species are also widespread. In contrast, as there are over 300 unique species of fish and shellfish commercially farmed globally and, as the industry is relatively young, there are still major regional and national differences in aquaculture species, practices and diseases. However, this is changing as we can already see that species and disease problems are becoming increasingly similar between Norway and Chile for salmonids, and between Ecuador and Southeast Asia for shrimp.