Which anglerfish relatives live in the deep ocean?

The deep-sea anglerfish relatives that inhabit the deep ocean are known as deep-sea anglers, which comprise 11 families within the superfamily Ceratioidea.1

Unlike other anglerfish species that typically live on the sea bottom, deep-sea anglers are adapted for life in the open ocean, where they swim about, albeit feebly. They are characterized by several distinct features:1

• Lack of pelvic fins: Unlike their shallow-water relatives, deep-sea anglers do not possess pelvic fins.1
• Sexual dimorphism: Only the females possess the characteristic "fishing rod" (a modified dorsal fin spine) tipped with a "bait," which is almost always luminous to attract prey in the dark depths.1
• Parasitic males: In three families, the males are significantly smaller than the females and live as permanent parasites, attaching themselves to the female by biting. Their bloodstreams eventually fuse, leaving the male entirely dependent on the female for nourishment.1

While the broader group of anglerfishes (order Lophiiformes) is often associated with the superorder Paracanthopterygii, it is important to note that the classification of these groups remains a subject of ongoing scientific study and revision.23