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Argulidae

The family Argulidae contains the carp lice or fish lice – a group of parasitic crustaceans of uncertain position within the Maxillopoda. Although they are thought to be primitive forms, they have no fossil record. The Argulidae are the only family in the order Arguloida (occasionally "Arguloidea"), although a second family, the Dipteropeltidae, has been proposed.