Shadow Dwellers: The Liopropoma Reef Basslets

Author: Scott W. Michael

The beautiful Liopropoma basslets, secreted within coral reefs in their native habitats, make fantastic additions to the reef aquarium. A world-renowned reef fishes expert surveys the varied species and their care requirements.

Elegant Shadow Dwellers

When you go diving on a coral reef for the first time, you cannot help but be overwhelmed by the spectacular diversity of fish life moving about the sunlit shallows—elegant, brightly colored species, like angelfishes, butterflyfishes, wrasses, and surgeonfishes.Liopropoma. These "wee groupers" are most at home in deep caves, under overhangs, and in the labyrinthine catacombs that permeate coral reefs.L. rubre) peering out from under shelving sheet coral (Agaricia spp.) on an early morning dive.

Serendipitous Discoveries

It should not be surprising that relatively few of the smaller reef basslets were known to ichthyologists before equipment was available to explore the world’s reefs. Most of the species collected before scuba were larger species taken with hook and line or by bottom trawls. However, some smaller species were acquired by more serendipitous means.

For example, the first collected specimen of the ridgeback basslet ( L. mowbrayi) was one that had washed up on a beach after a storm, a specimen of the wrasse bass (L. eukrines) was taken from the stomach of a grouper, a many-lined reef basslet (L. multilineatum) was cut out of an emperor snapper, and an aurora bass (L. aurora) was found in the belly of a moray eel. Predatory fish apparently have fewer problems finding these fishes than the average diver!

Reef Basslet Distribution

At present, there are 29 described species. The genus is represented in the Indian Ocean, Western Pacific to the Tropical Eastern Pacific, as well as the tropical Atlantic. The majority of the smaller species—up to about 2.8 inches (7 cm) standard length (SL)—are found in the western Pacific (11 species, with 19.

Japan and Hawaii

The epicenter of diversity for the larger, deepwater species—attaining a maximum SL of about 9 inches (22 cm) and living at depths in excess of 330 feet (100 meters)—is southern Japan, with seven species. Hawaii is also home to an endemic member of the genus, the aurora basslet ( As far as their depth distribution is concerned, many reef basslets are restricted to deep water. For example, some larger Liopropoma spp. of all sizes in this region).

Other Locations

Almost half of the smaller species from the Indo-Pacific were described in a revision of the genus by Randall and Taylor in 1988 (five species, to be precise).L. aurora), while five species are reported from the tropical western Atlantic. Also, two species are known from the eastern Pacific. The last two species described were given names in 2012: Randall’s reef basslet (L. randalli), from the Arabian Sea and eastern Indonesia, and the Cape Verdes basslet (L. emanueli), from the Cape Verde Islands in the Eastern Atlantic.

A number of other species are currently awaiting description. Liopropoma (e.g., L. japonicum, L. lunulatum, and L. maculatum) are restricted to rubble and patch reef bottoms at depths in excess of 330 feet (100 meters). One species, L. erythraeum, is found at depths where only submersibles dare go, up to 3300 feet (1000 meters) deep. Others are regularly found in the shallows (e.g., the pinstripe basslet [L. susumi] and Swissguard basslet [L. rubre]), and still others are occasionally found at lesser depths but tend to be more abundant on deep reefs, in excess of 100 feet (33 meters). For example, both the Swissguard and candy basslet (L. carmabi) have been found intermingling at depths as shallow as 40 feet (12 meters) off the island of Dominica, but L. carmabi is most common in 165 feet (50 meters) of water or more.

Reef Basslet Physical Traits

How about their physical characteristics? All of the reef basslets are elongate with a pointed snout and a broad head that is almost flat on top. Two very interesting Liopropoma features are the tubular nostrils and the series of sensory pores on the head.

Most of the smaller Liopropoma have two distinct dorsal fins. However, some larger members of the genus have a single, continuous fin (these may be placed in the genus Pikea in the future). To make matters a bit more confusing, Swale’s reef basslet (L. swalesi), which is more similar to smaller members of the genus than the potential Pikea spp., also has a continuous dorsal fin.

Gender and Spawning

The members of the genus are gonochorists (that is, they do not change sex), but many of their close relatives are simultaneous hermaphrodites. It is thought that gonochorism in the There has been some success getting them to spawn in captivity, but no one has yet raised the larvae and offered them for sale.

Speaking of Liopropoma evolved from a hermaphrodite relative. At least two species (L. mowbrayi and L. rubre) have been observed courting or spawning at dusk. They make a quick dash above the substrate and release their eggs into the water column.Liopropoma larvae, they are distinct, spectacular little creatures, sporting a long dorsal fin. In some species, the spine comes complete with dangling ornamentation.

Reef Basslets Go Mainstream

Aquarists have been more fortunate than non-aquarium-keeping aquanauts when it comes to So, why the sudden increased availability? There are several reasons to explain it. First of all, the popularity of reef aquariums resulted in a shift in the types of fishes being collected. Back in the 1960s, ’70s, and even early ’80s, larger, showy fish were all the rage. The vast majority of North American aquarists had fish-only tanks, and most of them were home to lionfishes, anemonefishes, angelfishes, butterflyfishes, surgeonfishes, triggerfishes, puffers, and so on. Smaller, attractive fishes were just not as sought after by most, so they were not targeted by collectors.

When aquarists started devoting their tanks to growing coral gardens, there was a change in the kinds of fishes aquarists were interested in. Reefkeepers started looking for smaller fish species that did not harm the ornamental critters included in these invert-rich systems. The anthias, dottybacks, zooplankton-feeding wrasses, gobies, dartfishes, dragonets, and blennies started receiving more and more attention, and collectors became aware of this demand. Today, you can look at any fish wholesaler price list and see almost as many diminutive, "reef-safe" species as you do large, showy fishes.

Rare Species Become Popular

The several years after reef aquariums exploded onto the marine scene, courageous collectors began seeking out rare species on deep reefs in the tropical western Atlantic. Rather than breathing compressed air, these individuals began employing more modern diving techniques that would allow them more time at depth (namely trimix and rebreathers).


The final chapter in the Liopropoma encounters. While these fish were once few and far between in the aquarium industry (with only one species, the Swissguard basslet, showing up rarely), now a number of species are commonly seen in the ornamental fish trade. Liopropoma rode this reef-safe tsunami, and at a least one species (e.g., our good buddy L. rubre) began showing up with even greater regularity.

Liopropoma that prefer deep reef slopes, including the incomparable candy basslet. Most of these Liopropoma were exported to Japan, where they were sold for big money. A few wafts made it into the North American market (e.g., in 1997, I bought an L. carmabi that was missing one pectoral fin for around $400). While not collecting fish for the aquarium trade, deep-diving ichthyophiles, like Dr. Richard Pyle and John Earle, were collecting a handful of new western Pacific Liopropoma at this same time, in that area of the deep reef referred to as the "Twilight Zone." Liopropoma saga began about 10 years ago. This was when the little-known Swale’s reef basslet (L. swalesi) began showing up in aquarium stores.

When the genus was revised in 1988, this fish was known from four specimens and no photos were available of live specimens. It was being peddled as a "poor man’s" candy basslet. While not as stunning as L. carmabi, it was only about one-tenth the price. As they became even more available, the price dropped until they were about the same cost as the ever-present Swissguard basslet. Not long after, L. swalesi began showing up with some regularity, so too did a number of other Indo-Pacific congeners, including a couple of species that had yet to be formerly described (e.g., yellowtail reef basslets). To date, I have seen 12 different species in the aquarium trade.

Questionable Collection Methods

We know why this final surge of It seems logical that the chemical of choice in the western Pacific would be sodium cyanide. This can be lethal not only to some of the targeted species, but also to other organisms that share their refuges. More sophisticated fish collectors and scientists use other chemicals with less deleterious side effects, such as clove oil (eugenol) and quinaldine, but these are more expensive and unavailable to poor fishermen in the Philippines and Indonesia.

I cannot help but wonder whether the popularity of the western Pacific There is another downside to the deepwater Liopropoma occurred, but how did it happen? As we discussed earlier, these are difficult fish to even find, let alone catch. While I have never been able to confirm this, I believe that the collectors became aware of the genus’ desirability and began using more aggressive (and potentially damaging) methods to capture these fishes. Because they are so secretive, I speculate that the only way to capture them in the numbers that we now see in the trade is to use a chemical to drive them out of their hiding places (as scientists use ichthyotoxins when sampling cryptic fish communities).

Liopropoma has not been bad for certain microhabitats and the reclusive species that co-habit them along with the reef basslets. Another byproduct of the L. swalesi blitz has been that other very cryptic fishes have been showing up, including soapfishes in the genus Suttonia, the spiny basslet (Belonepterygion fasciolatum), and more pseudochromoid fishes in the genera Lubbockichthys and Pseudoplesiops.

Liopropoma coming out of the western Pacific—namely, the two species that are pink with yellow tails, both of which are awaiting formal description. Because these are harvested at greater depths, properly decompressing the fish is critical. While I have not kept a "boatload" of yellow-tail reef basslets on which to base my conclusion, the specimens I have worked with all had swim bladder disorders, most likely resulting from improper decompression.

These fish had a difficult time maintaining their position in the water column. When not secreted in a crevice, they would struggle to keep from floating upward and would swim with the tail at a higher level than the head. If you are tempted to acquire one of these fish, make sure it has been in captivity for a week or more before purchasing it, as this condition can take a while to develop. Fortunately, this does not tend to be a problem with deepwater Liopropoma collected in the western Atlantic.

A Fish with Special Needs

It is interesting to look at the "old" aquarium literature and see what they said about the reef basslets. For example, a book written in 1976 (by Klocek and Kloman) says that I personally appreciate fish that are not as dauntless in their presentation. Audacious angelfishes that strut along the front aquarium glass soon begin to bore me. I like fish you have to work to observe, or that offer only an occasional glimpse. Such fish rarely overstay their welcome, because you often forget they’re in the tank.

Of course, not everyone shares my opinion. If you do like more showy fishes, choose your You are going to be able to enjoy these hyper-secretive species more if you keep them in a nano-reef aquarium. It is simply easier to find them in a smaller tank. If you do house them in a larger reef tank, try searching for them during the crepuscular phase of your aquarium light cycle (i.e., when the blue actinics are the only lights on over the tank), with all other lights in the room extinguished. You can also replicate the deep reef habitat that many of these fish are accustomed to by simply illuminating the tank with less-intense lights (e.g., actinics only). In this way, your more secretive reef basslet will spend more time in the open.

L. carmabi

One last thought on this subject: Even the most showy L. carmabi "is very delicate in captivity, and acclimates to prepared foods with difficulty." The author goes on to say that other species in the genus "are infrequently offered to aquarists due to the delicate nature and rarity of the fishes." In the pre-reef days, this may have been another reason the few Liopropoma available never gained popularity with aquarists.

Wild vs Captivity

Placing a smaller reef basslet in an aquarium with big, bold fish and relatively few hiding places equates to a death sentence for these relatively peaceful, timid fish. In the invertebrate aquarium, the reef basslet found a comfy home, more similar to its natural microhabitat—that is, lots of crevices and small caves in which to skulk. Liopropoma spp. carefully.

While all are very secretive in the wild, they vary in their reclusiveness in captivity. For example, the candy and ridgeback reef basslets are relatively bold as Liopropoma go. In contrast, Collette’s (L. collettei) and Swale’s reef basslets are very reclusive. To give you an example of how withdrawn they can be, I have a friend who has an L. swalesi in a 75-gallon (284-liter) reef tank. He sees the fish about once a month, and he once went for several months without seeing it at all. In fact, he was sure it was dead! Liopropoma species is not likely to be seen much if the tank is situated in a high-traffic area, and none of these fishes will be as showy as an angel or butterflyfish.

No-Fuss Feeding

Feeding these highly withdrawn fishes would seem to present problems, but somehow, most individuals seem to find enough to eat. No doubt, they prey upon small crustaceans, and possibly worms, that reproduce and grow among the live rock. They may also snap up the occasional morsel introduced for their more-showy neighbors.

If you are worried about feeding a reef basslet you have not seen, you may try to direct some food into its favorite hangouts. Feeding is always easier in a nano-reef, and this is one reason I think they are best suited to this captive venue. They will eat frozen mysid shrimp, vitamin-enriched brine shrimp, and various other fish foods. The larger species, which are not as common in the aquarium trade, will eat ornamental shrimps and even fish they can swallow whole, while adults of some of the smaller species are a threat to nano gobies and other Lilliputian tankmates.

Timid but Intriguing

If you have not taken the plunge yet and kept one of these shadow dwellers, I would say you have missed out on learning more about a very fascinating group of fishes. Sure, you may not see them all the time and, in some venues, they may perish prematurely, but if placed in the right setting, they can be long-lived, intriguing piscine pets.

But there is a secret underworld on coral reefs that most divers are unaware of—the cryptic ichthyofauna that live deep in reef caves, cracks, and crevices. This reclusive group includes many eels, brotulids, cuskeels, scorpionfishes, perchlets, soapfishes, roundheads, pseudochromoids, cardinalfishes, and gobies that may have never been seen by human eyes because of their secretive lifestyles. Another group of fishes that belong to this cryptic clan but can make fascinating aquarium residents are the reef basslets of the genus.

Many reef basslets seem to prefer steep reef drop-offs, which are often replete with expansive overhangs and large caves. The diver is unlikely to even encounter one of these fishes unless he or she employs a flashlight to illuminate their lairs. When caught in the glare of a diver’s light, a reef basslet may stay still for a few seconds, but will quickly regain its composure and begin dashing about looking for another shadowy hideout. There is also a chance you may see a reef basslet at the opening of a crevice, especially at dusk, when they tend to show themselves as they search for potential mates. For example, I have seen individual Swissguard basslets

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