Abantennarius nummifer

Lore & Background

The spotfin frogfish was first formally described as Chironectes nummifer by the French zoologist Georges Cuvier, with its type locality being unknown. The 5th edition of Fishes of the World classifies the genus Abantennarius in the family Antennariidae within the suborder Antennarioidei within the order Lophiiformes, the anglerfishes. The genus name Abantennarius prefixes ab, meaning 'away from', onto antennarius, a fish of the family Antennariidae, alluding to the gill opening being positioned away from the base of the pectoral fin. The specific name nummifer is a compound of nummis, meaning 'coin', and fero, meaning 'to bear', an allusion to the large brown spot on the second dorsal fin.

The spotfin frogfish has three dorsal spines, a second dorsal fin with 12 or 13 soft rays, and an anal fin with 7 or 8 soft rays. Its iliicium is about the same length as the second dorsal spine and bears an esca that is bulb-shaped with filaments, resembling a fat shrimp. It has a caudal peduncle, and the rear of the dorsal and anal fins are connected to the outer rays of the caudal fin by a membrane. The skin has no scales but is densely covered with forked spinules. The pectoral fins are prehensile with an elbow-like joint, and the gill opening is on or near their base. Overall colour may be yellow, rusty, pink, or red with a brown or reddish brown head, fading to brown or greenish brown on the body and fins, with a scattering of irregular greenish white blotches. The base of the second dorsal fin almost always has a dark spot surrounded by an indistinct greenish ring.

The spotfin frogfish is associated with reefs and is found as deep as 293 m, though typically at depths less than 20 m, with Atlantic populations in deeper waters than those in the Pacific. It can be found in the intertidal zone on reefs in lagoons and on seaward reefs.

Reader's Guide

The spotfin frogfish is notable for its wide but scattered distribution across the eastern Atlantic, Indian, and western Pacific Oceans, recorded from locations including the Azores, Madeira, the Canary Islands, Saint Helena, the Red Sea, South Africa, Madagascar, the Mascarenes, Seychelles, Maldives, the Persian Gulf, the Society Islands, Hawaiian Islands, Australia, northern New Zealand, and Japan. Its taxonomy places it within the family Antennariidae, order Lophiiformes, and its genus name reflects a distinctive anatomical feature: the gill opening positioned away from the pectoral fin base. The specific name nummifer refers to the coin-like dark spot on its second dorsal fin, a key identifying mark.

Ecologically, the spotfin frogfish is an oviparous piscivore. Females lay egg masses within ribbons of gelatinous mucus known as egg rafts or veils; one captive-laid raft was estimated to hold 48,000 eggs. The larvae are planktonic and settle onto the reef after one or two months. It attracts prey with its shrimp-like esca, luring fish within striking range. Its maximum total length is 13 cm, and it inhabits reef environments from the intertidal zone down to 293 m, though typically shallower than 20 m. The species' ability to inhabit both shallow and deeper waters across a broad geographic range highlights its adaptability within reef ecosystems.

Did You Know?

• The specific name nummifer means 'coin-bearing', referring to the large brown spot on the second dorsal fin.
• The gill opening is positioned away from the base of the pectoral fin, unlike in most frogfishes.
• A captive-laid egg raft was estimated to contain 48,000 eggs.
• The esca (lure) is bulb-shaped with filaments and resembles a fat shrimp.