What is "medusafish"

n. Any of the family Centrolophidae of perciform fish, often found in association with jellyfish.

Medusafishes are a family, Centrolophidae, of perciform 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.