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Issue: October 2009

Hardy and Fashionable: The Harlequin Tuskfish

Author: Bill Rosser

Ross T 1009
Photographer: Ed Wong
As if its incredible, vibrant coloration and otherworldly blue tusk-like teeth weren't enough, this unique-looking wrasse is actually hardy and acclimates well to aquarium life. A tuskfish fan describes his experiences with Choerodon fasciatus, which may just be the perfect specimen for the fish-only marine aquarium.

The perfect aquarium exists in the heart and mind of every marine aquarist. Upon entering the marine aquarium hobby, one dreams of establishing an aquarium teeming with an assortment of life—of different shapes, sizes, and colors. People who have had their aquarium set up for years are always on the lookout for that unique specimen that acts as a centerpiece or highlight for their aquarium. For those with a fish-only marine aquarium, the harlequin tuskfish is just such a fish. 

Background

Choerodon fasciatus is a moderately sized member of the wrasse family Labridae, attaining an adult size between 8 to 12 inches. Harlequin tuskfish get their common name from their harlequin-like colors and large, protruding teeth. The four front teeth have the appearance of small tusks, which will turn dark blue as the fish matures. It uses these teeth to puncture and tear the exoskeletons of the invertebrates it preys upon.

Healthy specimens boast a copper-toned set of orange and silver to greenish bands. These bands are often separated by thin, blue stripes. The bands darken and become more intense as the fish ages. Often the fins are a hue of red with a blue pinstripe bordering them. Juveniles are not as brilliantly colored and will appear pale in comparison to a mature adult. They also have black spots on their fins called eyespots for deterring would-be predators from the vital parts of the young fish.

Harlequin tuskfish have large orbital eyes that move independently from one another, allowing the fish to completely assess their environment. Put these characteristics together, and they produce a strikingly beautiful fish. Despite their large, fierce-looking teeth, they are mellow with almost comical behaviors, making them an excellent choice to add to any fish-only tank.

C. fasciatus is native to the subtropical and tropical waters of the Indo-Pacific. They can be found throughout much of the western part of the Pacific Ocean, with a range stretching from Taiwan to the Great Barrier Reef of Australia. Harlequin tuskfish spend most of their days patrolling habitats ranging from the open ocean to seagrass beds and reefs in search of food, which consists of various invertebrates such as shrimp, crabs, mollusks, urchins, and starfish. They will also consume smaller fish when the opportunity presents itself.

Most harlequin tuskfish available to the marine aquarium industry have been collected from either Australia or the Philippines. Due to collection and shipping techniques, specimens available from Australia tend to fare much better in the confines of an aquarium. For this reason, it is wise to attempt purchasing one with Australian origins whenever possible. Australian specimens are also much bolder in color. 

Reproduction

Information regarding reproductive habits of this species in the wild, let alone in the aquarium, is minimal. Harlequin tuskfish are protogynous hermaphrodites; all fry start life as females and are capable of changing their sex to a male. Research suggests that they form harems and, as a rule, the largest female in a harem will develop into a male as it approaches maturity or if the need for a male arises, such as if the male in a harem falls prey to a predator. A harem is a number of female animals who mate and live with one male. They likely spawn in open water, producing a large number of pelagic eggs that will drift with plankton in the currents until they settle in a reef or seagrass bed. Pelagic-spawning fish are among the most challenging types of marine fish to propagate in captivity.

Aquarium Conditions

After the initial acclimation process, harlequins make a hardy addition to any marine aquarium. With proper care, C. fasciatus can live in excess of 10 years. An individual adult specimen should be kept in an aquarium no smaller than 75 gallons, but larger is always better and recommended. If you want to keep several specimens, you will need a much larger aquarium. Tuskfish are best kept in a fish-only-with-live-rock aquarium. Due to their diet of various motile invertebrates, they are not generally suitable for a reef aquarium. While coral and other sessile invertebrates would be safe, shrimp, crabs, urchins, starfish, small fish, and snails are all on the menu and would likely be consumed with gusto. Therefore, harlequin tuskfish are best kept with other large, moderately aggressive, and territorial fish. Tangs, angelfish, grunts, eels, puffers, and triggers are all acceptable tankmates, assuming they are of similar size. Make sure to introduce the tuskfish before the others to avoid territorial squabbles and bullying. C. fasciatus tends to not be as aggressive as other species and may not cope well with the constant harassing of an angry tang or angelfish that feels its territory is being invaded.

The ideal aquarium should provide ample amounts of visual barriers, dart holes, and overhangs, but not so much that swimming is impeded. Tuskfish are large and will be active throughout much of the day. They appreciate having large amounts of open water in which to cruise and swim. If they feel threatened for any reason, they will be grateful for a dark place to seek refuge. Regardless of how the rockwork is laid out, the primary goal is to provide shelter, security, and swimming space for the fish while allowing easy maintenance of algae and access to equipment within the tank.

The aquarium should be well filtered and circulated, and the water parameters must be monitored on a regular basis. Water quality should be maintained in optimal conditions to keep the fish long term. As recommended with every other marine fish, water parameters should fall within a particular range. The specific gravity can be kept within the wide range of 1.018 to 1.025, depending on whether the aquarium is fish-only or reef. The pH should be kept at 8.2 to 8.4. Alkalinity should be between 3.5 to 4.5 meq/L (or 10 to 12 dKH). Ammonia (NH3) and nitrites (NO2) should be zero or as close to that as possible, as these can be very toxic even in low concentrations. Nitrates (NO3) should remain as close to zero as possible but are acceptable up to 10 ppm. The aquarium temperature should be 77° to 80°F. It is important that this temperature does not fluctuate rapidly (i.e., several degrees in an hour or two, such as when the lights come on and go off), as this will cause the fish undue stress. While the water temperature of natural seawater does change, it does so very gradually over several days or even weeks, allowing animals to slowly adjust to the changes.

While Choerodon fasciatus is likely to live in harems, they tend to be loosely formed, and individuals allow plenty of space between themselves and other members of the group. Keep in mind that in the ocean there are infinite opportunities for these fish to escape one another if need be. Their territoriality can cause problems in the average-size home aquarium, however, as escape is restricted to areas within just a few feet, with limited areas for shelter and refuge. For this reason, it is best to only have one tuskfish per aquarium. In order to keep a group, it is best to acquire at least a half dozen or so specimens at a very small size and house them in an extremely large tank.

Tuskfish that are 4 inches or larger may have already changed to a male. By purchasing fish 4 inches or less, you increase your chances of acquiring all females, thus allowing one to change to a male. They should all be acclimated to the aquarium at the same time. As the fish grow, hopefully a harem will develop with one male and a group of females. While aggression will likely still exist, disputes should be brief and minimal assuming the tank is appropriately sized. A minimum-size tank would be at least 180 gallons with plenty of visual barriers and hiding places. Once again, a larger aquarium is always better. Successfully keeping a group of these fish is almost unheard of but not impossible with research and proper conditions. 

Feeding

C. fasciatus will thrive on a diet that is well varied. The bulk of the diet should consist of frozen foods. The majority of tuskfish that have been collected from Australia acclimate to captivity and will start feeding with little effort. Nonetheless, there are always exceptions. If you happen to get a finicky feeder, many harlequin tuskfish cannot ignore live glass shrimp (or peppermint shrimp, if you can afford a pricy meal). Clams on the half shell are also very effective in inducing a feeding response. Never offer common feeder goldfish, as these quickly lead to malnutrition and head and lateral line disease. Mollies acclimated to and/or raised in salt water may be used, but tuskfish should be weaned off of those as soon as possible and onto a more nutritious diet. Most tuskfish will not eat pellets initially, but they will eventually learn to accept them. Try to purchase a fish that you have seen eating frozen foods. Ask to see it feed if possible.

Readily available frozen food items include fish, invertebrates, and gelatin formulas. Eventually, their diet should consist of shrimp, krill, prawn, plankton, squid, octopus, clams, silversides, etc. Any food offered should be chopped into bite-sized portions. Several manufacturers distribute various gelatin formulas made for angelfish, triggers, tangs, etc., which may be incorporated into the diet. Many of these are rich with an assortment of ingredients. All frozen food should be soaked in a quality vitamin supplement prior to use and offered two to three times daily. 

Conclusion

Keeping beautiful, healthy marine fish in the home aquarium is the goal of every hobbyist. As advances are made in technology and husbandry, more and more people are entering the marine aquarium hobby each day. It should be no surprise that upon seeing a harlequin tuskfish for the first time, one will be captivated by its brilliant colors and almost comical attributes. Combine their bold presence, mellow nature, and general hardiness, and you get the perfect candidate for a show-quality resident of your aquarium that is sure to be noticed and admired by all who see it for many years into the future.



See the full article on TFH Digital http://www.tfhdigital.com/tfh/200910/#pg93

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