Red Worms in Fish

The red worm found in the muscle and internal organs of trout and redfin in particular is a nematode worm called Eustrongyloides. The worms are 20-30 mm long and are often in clumps in the flesh. The parasite can only infect other animals, including humans,  that eat uncooked or undercooked fish infected with these worms.

Advice is to freeze the fish first, which will kill the worms, and they can be removed from the fish. The fish should always be fully cooked at high temperatures; and never eaten raw or under cooked.

Provided the fish is fully cooked, the worms do not affect the eating quality of the fish.

The worms are spread by birds feeding on infected fish and transferring live worms through their faeces into the water.