Publication - Factsheet

Diseases of wild and farmed Finfish

Published: 17 Dec 2019

Some fish and shellfish diseases of particular significance in Scotland.

Diseases of wild and farmed Finfish
Parasitic Nematodes

Nematodes parasitic in wild marine fish are extremely common with species belonging to the genus Anisakis appearing to be the most abundant of the marine anisakines.

As a genus Anisakis has a worldwide distribution occurring in all the major oceans and seas although Anisakis simplex is generally only found in the temperate waters of the North Atlantic, North Sea and Baltic. 

In marine fish the commonly observed L3 stage are often found coiled in the viscera and/or musculature and are pinkish/white, cylindrical and tapering at either end with a small white spot on the anterior third of the body and measure 20 – 30mm. 

The parasite has also been linked to a condition in Altantic salmon called  Red Vent Syndrome (RVS) where large numbers of the parasites are found in a small area in the muscle surrounding the vent resulting in often severe lesions around the vent region.