A small genus of labrid fishes is regularly among the most popular fish for small marine aquariums. Although the genus lacks a common name, I'll refer to these regularly imported and sometimes misunderstood fish as "The Lined Wrasses" for reasons that should be obvious, once you get a chance to view a few photos. These small colorful wrasses have attractive patterns, mostly consisting of horizontal stripes, although one species has vertical stripes and one lacks stripes entirely. In addition to their small size and attractive looks, they are active fish. But are these personable fish right for every aquarium? Welcome to the August edition of "Fish Tales" and a look at the genus Pseudocheilinus.

Meet the Family

Pseudocheilinus is one of 60 genera within the Family Labridae, one of the largest reef fish families, which contains over 500 species and is second only to Gobiidae in total number of species. All wrasses, with the exception of Conniella apterygial, swim with their pectoral fins (Michael, 1998).

Within the recognized nine subfamilies of Labridae (Norman, 1957) is the subgroup or "tribe" called the Cirrhilabrini. Six genera are members of this tribe, of which Pseudocheilinus is one. All six of these genera (see below) share a unique eye structure, which is limited to these genera. This "double pupil" is the result of a division of the scleral cornea, which creates two equal halves (Springer and Randall, 1974). It is hypothesized that the anterior portion may well serve as a macro lens of sorts, which might aid these fish in the predation of small benthic invertebrates (Randall, 1999).

Genera of the tribe Cirrhilabrini

Cirrhilabrus	Pseudocheilinus
Conniella	Pseudocheilinops
Paracheilinus	Pteragogus

In addition to the specialized pupil, the seven members of Pseudocheilinus are characterized as having three or four pairs of recurved canine teeth on the anterior position of the upper jaw. The lower jaw has a single pair of canines up front, and then a series of small conical teeth on the inside. As can be expected, the design of the jaw structure aids in the capture of prey.

Originally, there was little confusion within the genus. The hardest part in reconciling this confusion seemed to be the problem with obtaining specimens of these often-secretive reef dwellers. Once the use of ichthyocide rotenone was established within the scientific community, knowledge of this genus increased greatly. Bleeker (1857) originally described Cheilinus hexataenia and later (1862) reclassified it as Pseudocheilinus. The genus remained monotypic until Jenkins (1901) described P. octotania and shortly thereafter Jordan and Evermann (1903) described P. evanidus. Quite some time passed before a new addition was recognized. In 1960, Schultz, et. al. described P. tetrataenia. This, apparently, is where the understanding of this genus became complicated. In 1970 Randall collected three additional species of Pseudocheilinus. However, it took 29 years for them to be officially recognized. The delay was a result of confusion over what is now known as P. octotaenia (Randall, 1999). Randall wasn't sure if this species was a single species of variable color patterns or more than one species. At the present time it is considered a singular species with numerous color patterns.

In the Wild

All seven species are represented within Indo-Pacific waters. Geographical distribution varies greatly amongst the species, with P. hexataenia having the widest range: from the Red Sea and eastern African coast stretching across the entire Indian Ocean and into the South Pacific to Tahiti and Tuamotu Archipelago. Pseudocheilinus evanidus has a distribution nearly as large, stopping just short of the Tuamotu Archipelago at the Marquesas Islands. On the flip side of the coin is P. dispilus, which has a distribution limited to Mauritius and Reunion Islands. Even though some specimens of this genus have been found down to 180 feet deep, most are found in water shallower than 60 feet deep. The exception, however, is P. ocellatus which is not found above 60 feet, and is only rarely noted above 100 feet of depth (Randall, 1999).

All species of Pseudocheilinus are coral reef dwellers. These small wrasses remain secretive and are rather difficult to approach underwater. They quite effectively hide in the small nooks and crannies created within a reef structure. Their main defense is simply to disappear within the rockwork. They will wedge themselves within this rockwork and remain hidden until the perceived threat is no longer a concern. The rockwork is also used as their sleeping quarters. All Pseudocheilinus spp. are diurnal, spending the evening inside a mucus cocoon, much like the fishes in the family Scaridae. This cocoon has been theorized to protect the entombed fish from predators while they sleep. Beyond providing a secure retreat, the reef structure also provides the prey for these wrasses. They are very effective predators of microfauna. Gut analysis of this species has revealed the staple of their diet to be small benthic crustaceans, such as copepods and amphipods. Isopods, small fish, crabs, shrimp, and polychaetes were also regularly noted in most species.

Individuals of Pseudocheilinus species are not only shy, but they are also solitary. Some adults may form loose aggregations, but even still, they do not interact as groups or harems, instead choosing to remaining a unsociable. Spawning reports seem to be non-existent, although it is presumed mating is done in pairs. Pseudocheilinus species are protogynous hermaphrodites, that is, all males were first functioning females. Various studies have been performed and have indicated overall size is a good indication of the sex of the animal. Generally speaking, a Pseudocheilinus that is one-third or less of its maximal expected length is still immature and does not have a sex. Animals between one-third and two-thirds of their expected adult total length are sexually functioning females, and thus, males are those individuals that are above two-thirds of their total expected adult length (Randall, 1999).

In the Home Aquarium

All Pseudocheilinus species make hardy additions to a reef aquarium. They remain extremely disease resistant, and once established inside an aquarium, are generally long-lived. Reports of Lined Wrasses living over 10 years are not uncommon. However, it is also not uncommon for these diminutive fish to become rather boisterous to the extent of becoming hostile. Once established in the aquarium, mixing additional fish, or even shrimp, can be an exercise of futility. Smaller fish may be consumed, while fish of equal size or slightly larger are likely to be harassed. Sometimes the harassment will subside after a few days, other times it will continue until the death of the targeted animal. In either case, it is best to take steps to avoid this confrontation. Some tips to minimize these problems would include adding the Lined Wrasse last, separating individuals with egg crate material until aggression has subsided, and designing the aquarium's aquascape to contain a lot of hiding places. In some cases the removal of one of the fish may be required to restore equilibrium. Maintaining individuals of two or more Pseudocheilinus species in the same aquarium is not recommended.

Compatibility chart for Pseudocheilinus:

Fish	Will Co-Exist	May Co-Exist	Will Not Co-Exist	Notes
Angels, Dwarf	X			Should mix well provided angel is in first.
Angels, Large	X			Good tank mates.
Anthias	X	X		Individual Anthias are at risk of harassment.
Assessors			X	Wrasse will likely continually pester them.
Basses	X			Good tank mates.
Batfish	X			Good tank mates.
Blennies	X			Most blennies can 'hold their own.'
Boxfishes	X			Good tank mates.
Butterflies	X			Good tank mates.
Cardinals		X		Cardinals in first, but wrasse may harass anyway.
Catfish	X			Good tank mates.
Comet	X			Good tank mates.
Cowfish		X		Small Cowfish are at risk of harassment.
Damsels	X			Good tank mates.
Dottybacks	X			Good tank mates.
Dragonets		X		Food competitors and Lined Wrasse will likely continually pester them.
Drums	X			Good tank mates.
Eels		X		Some species will mix; Larger specimens may consume Lined Wrasses.
Filefish	X			Good tank mates.
Frogfish			X	Larger specimens may consume Lined Wrasses.
Goatfish	X			Good tank mates.
Gobies		X		Wrasse will likely continually pester them.
Grammas		X		Wrasse will likely continually pester them.
Groupers		X		Larger specimens may consume Lined Wrasses.
Hamlets	X			Good tank mates.
Hawkfish	X			Good tank mates.
Jawfish		X		Wrasse will likely continually pester them.
Lionfish		X		Larger specimens may consume Lined Wrasses.
Parrotfish	X			Good tank mates.
Pineapple Fish	X			Good tank mates.
Pipefish			X	Food competitors and Lined Wrasses will likely continually pester them.
Puffers	X			Good tank mates.
Rabbitfish	X			Good tank mates.
Sand Perches		X		Large Sand Perches can consume Lined Wrasses.
Scorpionfish		X		Larger specimens can consume Lined Wrasses.
Seahorses			X	Food competitors and Lined Wrasses will likely continually pester them.
Snappers	X			Good tank mates.
Soapfishes	X			Good tank mates.
Soldierfish	X			Good tank mates.
Spinecheeks	X			Good tank mates.
Squirrelfish	X			Good tank mates.
Surgeonfish	X			Good tank mates.
Sweetlips		X		Larger specimens can consume Lined Wrasses.
Tilefish		X		Should be excellent tank mates.
Toadfish			X	Larger specimens can consume Lined Wrasses.
Triggerfish		X		Some Triggerfish require a species-specific aquarium.
Waspfish			X	Larger specimens can consume Lined Wrasses.
Wrasses		X		Will harass most other wrasses, the exception being larger, more aggressive wrasses.

Note: While many of the fish listed are good tank mates for Pseudocheilinus species, you should research each fish individually before adding it to your aquarium. Some of the fish mentioned are better left in the ocean, or for advanced aquarists.

Besides harassing decorative shrimp, individuals of Pseudocheilinus species are likely to pester crabs. In regards to the ornamental shrimp and crabs, it may be too late by the time you notice the damage being done. Both shrimp and crabs make up a small portion of their natural diet; so do not be surprised when they come up missing in a Lined Wrasse aquarium. It might be in your best interest to plan on not keeping these mobile invertebrates in combination with a Lined Wrasse. Also, the commensal crabs often found associated with Acropora species are likely to be hunted and consumed. Quite frequently, the fish will ignore these decorative mobile invertebrates for years, only to decide one day that they look like a tasty morsel. Once a Lined wrasse becomes a shrimp/crab eater, it can be expected to remain as such throughout its life. It would be wise to forego the thought of maintaining these invertebrates or remove the wrasse. The attacks on mobile invertebrates likely stops there, with the exception being small snails that are brave enough to venture out during the day. Typically, no predation is displayed upon sessile invertebrates.

Of course, before worrying about whether it will mix with your planned inhabitants, it would be wise to visually inspect the health of the prospective fish. Avoid any fish with obvious signs of damage, especially around the mouth or fins. Likewise, ensure the fish is eating. Lined Wrasses should be alert and active in the dealer's aquarium, and should be feeding by actively searching the substrate and rockwork, as well as taking prepared foods from the water column.

Naturally, ensure your aquarium meets the requirements for successful husbandry. Aquarium size is not terribly important given the small size and shy nature of these fish. However, the aquarium must be large enough to meet several criteria. First, it needs to contain adequate hiding spaces. Lined wrasses are not outgoing fish, and will likely spend a great deal of time cruising through the live rock. Small caves, nooks, and crannies should be plentiful. Aquascape the aquarium to maximize the hiding places, given the amount of live rock at hand. In addition to hiding places, a high quality live rock will provide a good deal of natural foods. In situations where minimal live rock is present, these pod-hunters will decimate your small benthic invertebrate population in short order. Supplemental feeding should be increased and food competitors should be eliminated. These feedings should be focused around meat-based foods such as Mysis, plankton, enriched Artemia, and any other frozen/thawed or freeze-dried foods available to the aquarist that are geared towards carnivores. Lastly, smaller aquariums likely contain small fish like gobies, or fish that maintain minimal territory requirements such as jawfish. However, be advised that it is these same fish which the Lined wrasses are most likely to pester. Therefore, choose aquarium inhabitants carefully.

Meet the Species

By far the most popular Pseudocheilinus is P. hexataenia, or the Six-Lined Wrasse. The relatively shallow water they inhabit, combined with their easily explains why they are the most regularly available Lined wrasse. Most are located above 40 feet of depth, with the majority located shallower than 10 feet on some reefs.

The diet of this species is widely variable, with stomach contents containing such items as foraminifera, copepods, amphipods, gastropod eggs, gnathiid and idoteid isopods, shrimp and shrimp larvae, and mysids. Sano, et al., (1984) concluded this species consumes mainly demersal planktonic crustaceans, but feeds occasionally on crustacean ectoparasites of other fishes.

The largest specimen studied thus far has been 61mm. For those concerned about the sex of their fish, all specimens measuring 35mm and up were determined to be males, those in the 25 - 30mm range were mature females, and those in the 21 - 27mm range were immature (Randall, 1999). This obviously lends support to the belief of protogynous hermaphroditism.

The Four-Lined wrasse, P. tetrataenia, is another regular import. Distribution is throughout both the tropical North and South Pacific Oceans. Like the Six-Lined, it is a shallow reef dweller. It prefers to stay tight to the outer reef slopes and is most often found associating with the coral Pocillopora meandrina (Randall, 1999). Rarely does this species venture more than several inches to one foot above the substrate. Stomach contents of this fish were also highly variable, though somewhat selective. One fish was noted to have only the remains of a Pistol Shrimp (Alpheus sp.), while another contained a crab, and yet a third had only shrimp and gastropod larvae.

Pseudocheilinus tetrataenia held true to protogynous hermaphroditism when researched. The largest individuals (up to 102mm) were always male, the smallest were immature, and those in the middle were female. Interestingly, one specimen that was 42.5mm had the tissue of both the female reproductive organs as well as that of the male (Randall, 1999).

The Eight-Lined Wrasse, or P. octotaenia, is not nearly as regularly imported as the two aforementioned Lined wrasses. These are among the largest Lined wrasses, roughly 127mm at adulthood, and consequently their diet reflects this. Stomach contents revealed two specimens dining exclusively on small fish, another on crabs, and a third split between shrimp and gastropods (note, I did not say 'larvae'). This species is rather variable in color patterns, and at one point some confusion existed because of the multi-color patterns. Originally named by Jenkins (1901), it was subsequently renamed by Smith (1955) as P. margaretae. Schultz (1960) moved P. margaretae into synonymy with P. octotaenia.

The Five-bar Wrasse, or P. ocellatus, is likely considered the most attractive of all the Pseudocheilinus. Distribution is sporadic throughout the tropical North and South Pacific Oceans and is generally limited to deeper waters than the common Lined wrasses inhabit. Most specimens are located from 90 to 120 feet of depth. Their sporadic distribution, combined with the depth at which they are acquired, combine to make this Lined wrasse the most expensive of the genus. Four inches of length at adulthood should be expected for these wrasses.

Conclusion

Oftentimes hobbyists are excited upon seeing their first Lined wrasse. Their small size and adorable stripes usually make for a quick impulse purchase. They mistakenly assume it'll mix well into any aquarium, and eagerly take it home. Only after it becomes aggressive will the hobbyist do a quick search and discover that this behavior was to be expected. The hobbyist is then faced with the unpleasant duty of trying to capture a small, fast, nimble fish. It is not an easy task! Arming yourself with this knowledge before the purchase will save many headaches down the road. For those reading this after their purchase, may I recommend a good fish trap link?

References:

Michael, S.W. 1998. Reef Fishes Volume 1. Microcosm. Shelburne, VT. pp. 624.

Norman, J. R. 1957. A Draft Synopsis of the Orders, Families, and Genera of the Recent Fishes and Fish-Like Vertebrates. British Museum (Natural History), London. 649 pp.

Randall, J. E. 1999. Revision of the Indo-Pacific Labrid Fishes of the Genus Pseudochilinus, with descriptions of three new species. Indo-Pacific Fishes. Bern. Pau. Bish. Mus. 34pp.

Spinger, V. G. and Randall, J. E. 1974. Two new species of the labrid fish genus Cirrhilabrus from the Red Sea. Israel Jour. Zool. 23: 45-54