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Parasitic Diseases of Wild Fish

Parasitic diseases of fish such as Ichthyophonus, Nanophyetus salmincola, and whirling diseases pose a significant threat to fish populations.

Ichthyophonus is one of the most significant parasites of wild marine fishes, causing recurring population-level impacts during the past century. 

Nanophyetus salmincola is a freshwater parasite that infects snails as its first host, then fish as the second host, and finally birds and mammals and its primary host.

Nucleospora salmonis is a microsporidian parasite that infects the hematopoietic cells of salmonid fishes causing a leukemia-like condition. Infections have been reported in salmon and trout species.

Whirling disease is an infection of trout caused by the Myxobolus cerebralis parasite. The parasite penetrates the head and spinal cartilage putting pressure on the organ of equilibrium. This causes fish to swim erratically.

Ichthyobodosis is caused by the flagellate parasite Ichthyobodo necatorThe parasite is found globally and infects freshwater and marine fishes.  The parasite attaches to the gills and skin of the fish.