cymothoid

crustacean

Also known as: Cymothoidae

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Last updated

June 25, 2026

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The family Cymothoidae, a group of isopods within the class Malacostraca, are exclusively parasitic crustaceans that infest both marine and freshwater fishes. These parasites, often called crustacean lice, have developed strong thoracic claws to attach themselves securely to their fish hosts. They can be found on the fish's skin, under the gill covers, in the mouth, and in some South American species, even within the abdominal cavity. Their tenacious grip is so effective that they have occasionally been found in canned fish products, having survived the canning process.1

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crustacean louse
Of the latter, the family Cymothoidae (order Isopoda) is of special interest, as it is exclusively parasitic and infests both marine and freshwater fishes. Crustacean lice may live on the outer skin of the fish, under the bony covering protecting the gills, in the mouth cavity, and even within the…
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Of the latter, the family Cymothoidae (order Isopoda) is of special interest, as it is exclusively parasitic and infests both marine and freshwater fishes. Crustacean lice may live on the outer skin of the fish, under the bony covering protecting the gills, in the mouth cavity, and even within the…
Read More