Speaking of worms in fish, Investigator Stanley Sanpaul writes:
I talked to somebody who used to work in the fish department at my local store. He said
1. finding worms in fish is VERY common
2. worms are good in the following sense.
Squeeze lemon on the fish (before cooking of course). The worms don’t like the acid and will start popping out of the fish.
This indicates the fish is fresh.
Dead worms indicate older fish.
Helen Rennie, in the Beyond Salmon blog, concurs, but only sort of:
First of all, let me say that parasitologists are some of the kindest and most patient people I have ever met in academia. They were willing to explain fish parasites in terms that even I could understand and painstakingly answered all my questions. I learned that there are over a hundred species of parasites that can be found in fish, but only 3 of them are potentially harmful to humans: Pseudoterranova decipiens (a.k.a. “cod worm” or “seal worm”), Anisakis Simplex, and Tapeworm. Today, our special guest will be cod worm. I remember my first encounter with this critter about 4 years ago….
BONUS: The Gothamist weighs in about the worms-in-lox question.