Trematode infections in farm-raised fish: reasons for infections, their impacts, and management of infections on fish farms

Authors: Mitchell, Andrew; KHOO, LESTER - Mississippi State University

Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/5/2010
Publication Date: 7/10/2011
Citation: Mitchell, A.J., Khoo, L. 2011. Trematode infections in farm-raised fish: reasons for infections, their impacts, and management of infections on fish farms. Cipriano, R. C., Bruckner, A. W., and Shchelkunov, I. S. editors. 2011 Bridging America and Russia with Shared Perspectives on Aquatic Animal Health. In: Proceedings of the Third Bilateral Conference between Russia and the United States. 12-20 July 2009, Shepherdstown, West Virginia. Kahled bin Sultan Living Oceans Foundation, Landover, Maryland, USA. p.231-236.

Interpretive Summary: Trematode infections occur when parasite and fish, snail and bird hosts (three hosts for common fish trematode infections) occupy the same environment. The pond, the major production facility used to culture warmwater fish, provides this ideal environment. The resurgence of fish-eating bird populations and the loss of wet lands due commercial and residential land development have served to further concentrate these hosts on the production ponds. Losses have been reported by sunshine bass and baitfish producers, but more serious problems have occurred in the channel catfish industry where losses in excess of $25 million USD annually have been reported. Additionally, an exotic snail and its trematode counterpart from Asia have made their way to the US and impacted the tropical fish industry, causing an estimated annual impact of $3.5 million USD in 1996. Control measures are limited to aquatic snail management. Treatments that concentrate chemical solutions or suspensions (i.e., copper sulfate and hydrated lime) in the waters at the pond’s edge (the area of the pond where most snails live) have been effective. Net disinfection methods (hot water, cold water, and Roccal®-D-Plus dips) can help prevent the spread of exotic snails to new locations in the US.

Technical Abstract: The onset and rapid growth of pond aquaculture from the late 1940s, the loss of wet lands due commercial and residential land development, the resurgence of aquatic bird populations, and the importation of exotic snails and parasites have lead to digenetic trematode infestations in cultured fish. With these events, an ideal environment for the build-up and concentration of trematode hosts (birds, snails and fish) was found in warmwater fish-pond production facilities. Thus it was inevitable that trematode numbers cycling through these hosts would increase and produced disease outbreaks. As a result of the above mentioned factors and probably others, infections of the trematodes have been reported in pond raised fish throughout the southeast.