White-banded Possum Wrasse

Geographical Origin and Habitat: Widespread across the tropical Indo-Pacific, from East Africa and the Red Sea to the Hawaiian and Society islands, north to Japan, and south to Australia. Inhabits steep seaward reefs and lagoons rich in caves and crevices at depths of 8 to 42 meters.

Taxonomy and Morphology: Member of the family Labridae, genus Wetmorella. Body is laterally compressed with a pointed snout and large eyes. Adult size is exceptionally small, reaching a maximum length of only 6 cm.

Social Behavior: Peaceful, secretive, and highly timid. Spends most of the day hovering slowly near rocks or swimming upside down under overhangs. Thrives and becomes active in quiet, stress-free environments.

Coloration and Sexual Dimorphism: Reddish-brown or brick-red body adorned with two distinct vertical white bars and black ocelli ringed in yellow on the dorsal and anal fins. No obvious sexual dimorphism exists, though dominant males may be slightly larger.

Aquarium Setup: Perfect for nano-reefs starting from 80 liters. The tank must feature extensive rockwork with multiple caves, overhangs, and dark tunnels. Does not require a sand bed for sleeping, as it nests in rock cavities. A lid is recommended.

Diet and Feeding: Carnivorous. Feeds on small benthic invertebrates. In captivity, feed with small frozen foods like copepods, brine shrimp, and finely chopped mysis. Live foods may be needed initially to encourage feeding.

Water Quality: Stable marine parameters are essential: temperature 22-26°C, pH 8.1-8.4, specific gravity (SG) 1.020-1.025, GH 15-25, KH 8-12. Prefers low to moderate water flow areas within the tank.

Compatibility and Cohabitation: 100% reef safe. Coexists peacefully with other tiny, peaceful tankmates like gobies and pipefishes. Avoid large or aggressive fishes (e.g. surgeonfishes, large damselfishes) which will terrify it and cause starvation.

Aquarium Breeding: Protogynous hermaphrodite. Captive reproduction is undocumented due to its small size and secretive spawning habits.

Risks and Diseases: Starvation due to food competition with fast-moving competitors is the primary threat. Vulnerable to marine ich (Cryptocaryon) if subjected to chronic stress from aggressive tankmates.