Medusafishes are a family, Centrolophidae, of scombriform ray-finned fishes. The family includes about 31 species. They are found in temperate and tropical waters throughout the world.

Young Icichthys lockingtoni specimens are abundant in the coastal waters of the north Pacific, where they are often found in association with jellyfish, which provide them with protection from predators and opportunities to scavenge the remains of the jellyfishes' meals.

The oldest known fossil member of the group known from articulated remains is Butyrumichthys from the earliest Ypresian of the Fur Formation in Denmark. Slightly older fossil otoliths of the species "Mupus" sinuosus are also known from the Selandian of Denmark.

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