Nemapterois

Lore & Background

Nemapterois biocellatus was first formally described in 1938 by American zoologist Henry Weed Fowler, with the type locality given as off Jolo Light on Jolo Island in the Sulu Sea, Philippines. The genus name Nemapterois is a compound of nema, meaning 'thread', and Pterois, the genus of 'typical' lionfishes. The specific name biocellatus means 'two spots', alluding to the two eye-like spots (ocelli) on the soft-rayed part of the dorsal fin. Before 2023, this species was considered a member of the genus Dendrochirus, but it is now understood to be not particularly closely related to Dendrochirus species.

The species has 13 spines and 9 soft rays in its dorsal fin, with 3 spines and 5 soft rays in the anal fin. The middle spines in the dorsal fin are shorter than the depth of the body, with deep incisions in the fin membranes. The large, wing-like pectoral fins have 20 or 21 fin rays, with the upper rays fully connected by membranes and the lower rays simple with tips extending beyond the membrane. The tentacles on the lacrimal bone are long, more than two times the diameter of the eye. The overall color is reddish-brown, with 2 (sometimes 3) large black ocelli on the soft-rayed part of the dorsal fin, and 3 pink to yellowish bars on the flanks. The pectoral fins are banded with pale and brown.

In the wild, this species shelters in caves and on ledges during the day, emerging at night to feed on small fishes and small crustaceans. The fin spines are venomous. It has been observed to have unusual feeding behavior: as it approaches prey, it snaps its dorsal fin spines and shakes its head from side-to-side, which may distract or attract the prey. The fleshy tentacles on the upper jaw, which give it the name 'Fu-Manchu lionfish' in the aquarium trade, may also be used to attract prey. These fish stalk prey by moving stealthily along the substrate or around reef structures, moving forward by 'hopping' on the pelvic fins or sinuously waving its caudal fin until it is about half its body length from its quarry, then making a rapid lunge.

Reader's Guide

Nemapterois biocellatus is the only species in the monotypic genus Nemapterois, making it taxonomically significant within the family Scorpaenidae. Its reclassification from Dendrochirus to Nemapterois reflects ongoing refinement in understanding the evolutionary relationships among lionfishes. The species is widespread throughout the tropical waters of the Indo-West Pacific region, from the western Mascarene Islands, the Maldives, and Sri Lanka eastward to the Mariana and Tuamotu Islands, north to southern Japan, and south to New Caledonia and Tonga. In Australian waters, it is found at Scott Reef off Western Australia, at the Ashmore and Hibernia reefs in the Timor Sea, and at Christmas Island. It inhabits areas with rich coral growth on reefs in clear water at depths of 1 to 40 meters.

The species appears occasionally in the aquarium trade, where it is considered moderately difficult to keep and not for beginners. Its distinctive appearance, including the long tentacles on the upper jaw and the ocelli on the dorsal fin, along with its unusual feeding behavior, contribute to its appeal among advanced aquarists. The venomous fin spines require careful handling. The species' feeding strategy—using head-shaking and tentacle lures—represents a notable adaptation for capturing small fish and crustaceans in its reef habitat.

Did You Know?

• The specific name biocellatus means 'two spots', referring to the two eye-like spots on the dorsal fin.
• The fleshy tentacles on its upper jaw give it the common name 'Fu-Manchu lionfish' in the aquarium trade.