I bought some frozen Hairtail fish (Chinese: 帶魚) and one of them had some kind of isopod on it. I already removed the bug and threw it out, but after some research it looks a lot like the image here: https://en.wikipedia.org/wiki/Cymothoidae

Is it still okay to cook and eat the fish?

  • I don't understand the factors at play here enough to answer the question, but I have once read that fish are generally required to be frozen in such a way that kills the vast majority of parasites and renders them harmless. Here are some FDA guidances that may help you make an informed decision: fda.gov/media/80777/download Apr 7, 2021 at 22:14

3 Answers 3


It should be safe to still eat the fish, especially if you're going to be cooking it! IMO parasites like the isopod that you found are far less dangerous than less visible ones such as worms, flukes etc.

Quoting from: https://en.wikipedia.org/wiki/Cymothoa_exigua

C. exigua is not believed to be harmful to humans, except it may bite if separated from its host and handled.[14]

In Puerto Rico, C. exigua was the leading subject of a lawsuit against a large supermarket chain; itis found in snappers from the Eastern Pacific, which are shipped worldwide for commercial consumption. The customer in the lawsuit claimed to have been poisoned by eating an isopod cooked inside a snapper. The case, however, was dropped on the grounds that isopods are not poisonous to humans and some are even consumed as part of a regular diet.[9]

It seems to me that a closely analogous example to the isopod you found on fish are pea crabs in shellfish: https://en.wikipedia.org/wiki/Pea_crab. Though perhaps pea crabs are less parasitic to shellfish than isopods are to fish.

There was once I was having some cooked clams at a resto. When the clams were served, I found every single one occupied by at least one pea crab. They were cooked along with the clams. I just removed and discarded the crabs, the flesh of the clams was completely fine.


I'd say no.

Conventional wisdom suggest that when in doubt, throw it.

Throw it away, go back to your fishmonger/store and tell them about that.

If that fails, do not buy from that brand (if there's any brands attached to your frozen fish)

  • Surely if you take "when in doubt throw it out" to its logical conclusion you'd eventually throw everything out. You have to draw a line somewhere, and wherever it is there will be cases where you're not sure which side of the line they're on. If you always throw it out you'd shift that line.
    – bdsl
    Sep 18, 2021 at 21:40

Fish is such food that causes food poisoning quickly. And if you see something there, like isopods, or the colour is not okay, or it smells strange, it's better to through it away. Even if you cook it it doesn't guarantee you safety.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.