Whitebanded Possum Wrasse

From Microcosm Aquarium Explorer

Wetmorella albofasciata - Schultz & Marshall, 1954
Whitebanded Possum Wrasse

Wetmorella albofasciata.jpg

Shy, but a great species for peaceful reef aquarium. Scott W. Michael

Overview

Several small, secretive wrasses have been showing up in aquarium stores with greater frequency, among them the Whitebanded Possum Wrasse.

These are superlative reef wrasses. They particularly enjoy the many reef interstices and caves present in the invertebrate aquarium as well as the natural microfaunal fodder that is typically associated with live substrates.

It is possible to keep possum wrasses in a nano-reef tank, but you will need to feed them frequently as there will not be enough live prey items in a small tank to sustain them. You may not see them frequently if you keep them in a large reef aquarium, especially if it contains loads of live rock.

The major drawback with Wetmorella species is that they are quite reclusive. They spend most of their time moving among the rockwork. Occasionally you will see them peeking out of a crevice or a cave, or they may swim out to grab a passing morsel. While these wrasses are not likely to parade around the tank, they will become more bold once they have acclimated, if they are not picked on by piscine neighbors.

Unlike some of their larger cousins, they are not a threat to ornamental invertebrates.

Be sure you do not mistake the juvenile of the Slingjaw Wrasse (Epibulus insidiator) for the young W. albofasciata; the young slingjaw and this possum wrasse are very similar. The Slingjaw Wrasse gets approximately 35 cm (14 in.) in length and is a voracious predator.

Family: Labridae

Other common name(s):

  • Whitebarred Pygmy Wrasse

Native range:

Habitat: Wetmorella albofasciata is found on lagoon patch reefs, reef faces, and slopes at depths of 8 to 42 m (26 to 139 ft.). It is usually found under ledges and in caves and often swims with its belly oriented toward the cave ceiling. The possum wrasses are more likely to spend time in the open if kept in relatively quiet surroundings. For example, I had a 90-gallon reef tank in my office that contained two members of the genus. After a fortnight, I started seeing them moving about in the open quite frequently, but usually only when most of the room lights were off and I was working quietly at my desk. The tank had a large overhang and several small caves. I could often see the Wetmorella spp. moving along the edge of the overhang roof. If there was movement in the room, they stayed among the catacombs of the reef structure. Unlike some wrasses, the Wetmorella spp. do not bury in the sand at night, but simply "hole up" in the reef.

Maximum length: 6 cm (2 in)

Minimum aquarium size: 38 L (10 gal)

Water: Marine 23 °C (73 °F) - 28 °C (82 °F)

General swimming level: Near substrate.

Feeding

These microcarnivores will feed on tiny worms and crustaceans that associate with live rock. They also readily take aquarium foods, like Mysis shrimp, enrich ''Artemia'', frozen preparations, and flake food.

My Wetmorella seemed to prefer Cyclop-eeze, which they picked out of the water column. Even though they will eat introduced fodder, it is still best to house them in a tank with live substrate because they are so reclusive (especially when first added to a tank) and prone to being dominated by tankmates. This will enable the possum wrasses to feed throughout the day on the minute prey living on the rock. A productive refugium can also help to ensure that they get enough to eat.

Aquarium Compatibility

Not only are they shy by nature, they are also potential targets of tank bullies. It is best to avoid keeping them with more pugnacious species that may pick on them or with fishes that will prevent them from getting enough to eat. That said, I have noticed that many fishes simply ignore them.

The 90-gallon community tank mentioned above included a fairly pugnacious Redstriped Pacific Hogfish (Bodianus sp.), a Whitebarred Wrasse (Pseudocheilinus ocellatus), a Pinkstreaked Wrasse (Pseudocheilinops ataenia), and several fairy wrasses (Cirrhilabrus spp.). For the most part, the Wetmorella spp. did not elicit an aggressive response from their labrid tankmates. This may be due to the odd behavior, small size, and somewhat divergent body shape of the possum wrasses.

I did see the ''Bodianus'' nip at the eyespot on the anal fin of one possum wrasse on several occasions. I am not sure if the hogfish mistook the spot for a small prey item or if it was intentionally attacking the possum wrasse. In this fish community, it was obvious that the possum wrasses gave way to larger fishes and were at the bottom of the pecking order. I never saw them behave aggressively toward other fishes in the tank, including a Pinkstreaked Wrasse that was of similar size.

I rarely observed aggression between the two possum wrasses in my 90-gallon tank. However, I have seen larger Wetmorella bother smaller conspecifics in smaller tanks. In one case, a large individual continually harassed a smaller congener until the submissive fish spent all of its time cowering in the upper corner of the aquarium. If you plan on keeping more than one individual of the same species, or even congeners in the same tank, make sure the tank is large enough (e.g., 70 gallons or larger) and that it is replete with places for them to hide. Small holes are fine, but they really seem to appreciate caves and ledges. When there are aggression problems, the largest Wetmorella in the tank is likely to be the bully, no matter what species it is.

Breeding/Propagation

This wrasse usually occurs in pairs in the wild. Captive reproduction not yet reported.

Reference: Reef Fishes Volume 5
Image credit: SWM
Text credit: SWM