Fanfins are a family, Caulophrynidae, of anglerfishes. They are found in deep, lightless waters of the Atlantic, Indian and Pacific Oceans.

They are distinguished from other anglerfishes by the lack of the expanded escal bulb “” the bioluminescent lure at the end of the illicium “” and by the very long dorsal and anal fin rays.

As in other anglerfishes, males are very much smaller than the females and, after a larval and adolescent free-living stage, spend the rest of their life parasitically attached to a female.