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Strange Animal Fact: Fish Get Lice
Goldfish can live only in a freshwater environment.
Credit: Mashe | Dreamstime.com

Dogs get 'em. Cats get 'em. Even humans get 'em -- but fish? Yes, fish can get lice.

The "fish lice," or Argulus, are free-swimming parasitic crustaceans that usually enter fish ponds and aquariums as passengers on newly introduced fish or plants. Once inside of the habitat, the lice multiply and spread to the other fish.

The parasites attach themselves just below the fish's scales so that they can feed off of the fish while remaining mostly undetected. The lice look almost transparent, and often hide out behind the fish's fins or near its eyes and gills.

To feed they inject digestive enzymes into the fish's skin, which liquefies the flesh. They then suck out the liquefied flesh through their straw-like mouths.

This feeding process can cause the fish to experience major tissue damage and scarring. Lice bites can also make the fish more susceptible to bacterial infections. Fish with lice can develop anemia, and can even die from infected wounds.

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