Digenetic flukes are internal fish parasites and require two or more hosts to complete their life cycle. Trematodes can be found in cysts in the flesh or other internal organs. They also can live in the eye, blood, gills and other parts of the fish. Trematodes are rarely observed by anglers. These parasites are commonly observed by fishermen when cleaning their catch.
Larval tapeworms form cysts on or in the internal organs or in the body cavity.
Adults are white and worm-like and are found in the intestines. These parasites are rarely seen by fishermen. They live in the intestines of fish. Nematode or Roundworm Nematodes are very common parasites of fish. The larvae may be found in cysts or coiled in or on the internal organs.