Wednesday, June 4, 2008


A Kidako moray (Gymnothorax kidako) sporitng a Labroides mustache! A young bluestreak cleaner wrasse works over the eel, grazing on slime and ectoparasites. But how do these wrasses do in captivity? Scott W. Michael.

The cleaner wrasse genus Labroides is comprised of five very species that rely almost entirely on cleaning to obtain nutrients as both juveniles and adults. Cleaning behavior is defined as a mutualistic relationship that exists between certain parasite-picking fishes and their piscine neighbors (the client or host species). The cleaner wrasse removes parasites, and also some slime and scales, from the client fish. This benefit to the client is that it hosts fewer annoying parasites.

Although the cleaner wrasses vary somewhat in their aquarium suitability, most members of this genus are considered difficult to maintain long-term in the home aquarium. There may be one exception to this – it is the bluestreak cleaner wrasse (Labroides dimidiatus). Although we have long considered it difficult to keep this species in North America, unless it was held with numerous fishes on which to “graze,” the Europeans consider it a good beginners fish! It is so popular there, that in 2002 it was one of the top ten species exported to the European Union. The Europeans report some encouraging longevity records. For example, the Nancy Aquarium, France has kept L. dimidiatus for over 11 years, while a lifespan of over six years has been reported to me by several European reef-keepers.

The biggest problem with the Labroides involves feeding. With the possible exception of L. dimidiatus, most species reject captive fare. As a result, they rely totally on the ectoparasites and slime present on their fish tankmates to meet their nutritional needs. This may not be as big of a problem if you have a large tank that has lots of potential clients, the cleaner wrasse may be able to acquire enough nutrients by grazing slime, and the occasional parasite. But if there is relatively little grazing surface (i.e., fish bodies), then the cleaner will not get enough food to stay alive. Not all potential hosts are as valuable a food source as others (that is, those species that produce more slime are more desirable). Therefore, the types of fishes you keep the cleaner with may impact its chances of survival as well. Those species of cleaner wrasses (e.g., L. phthirophagus) that rely heavily on fish slime as a nutrient source, will usually perish in quick order in most home aquariums. There is an occasional cleaner wrasse (usually individual L. dimidiatus) that will accept foods like finely chopped shrimp, mysid shrimp, frozen brine, freeze-dried tubifex worms, or even frozen prepared foods, and flake foods. One way to induce a finicky cleaner to feed is to present them with a live or fresh mussel that has had the valves forced open so that they can pick at the “meat” within.

Cleaner Wrasse Pros and Cons

Unfortunately for the aquarist, cleaner wrasses do not consume the most problematic aquarium parasites - the protozoa and dinoflagellates. Therefore, cleaners are not recommended as a means of biological control of for ich (Cryptocaryon irritans) or velvet (Amyloodinium ocellatum) outbreaks. But cleaner wrasses will control another group of parasites that frequently infect our fishes. It has been shown that the cleaning behavior of the bluestreak cleaner wrasse can reduce the number of the monogenetic flatworms (Benedenia lolo) in aquarium-held fishes. (Food choice studies have shown that when given a choice of four different foods [mucus, parasitic monogenean flatworms, gnathiid isopods, and a control] the bluestreak cleaner wrasse fed more on mucus and monogeneans.) While the L. dimidiatus did not eliminate all of the flatworms, they did help keep their numbers in check. There is also evidence that indicates these wrasses will pick off the cyst-phase of the flatworm (Paravortex sp.), which is commonly referred to as black ich (a.k.a. yellow tang disease). As a result, the Labroides spp. may also aid in controlling the outbreak of this ectoparasite in a closed system. Finally, bluestreak cleaner wrasse will remove the cauliflower-like growths associated with the viral infection Lymphocystis.

But adding a cleaner wrasse to a tank of fishes also has a downside. There are some “costs” associated with visiting a cleaner wrasse. The Labroides feed on host mucus, scales, and skin, especially when ectoparasites are in short supply. Because most of the parasites on the cleaners bill-of-fare are in short supply in the home aquarium, the captive Labroides will ingest larger quantities of fish slime and scales in order to survive. Because of a loss of its external protection, a “captive client” is likely to be more susceptible to bacterial infections and infections by protozoa and dinoflagellate parasites. It is only logical that a cleaner is going to be more of a menace in a smaller tank that contains fewer potential clients to feed off of. Therefore, if you are going to keep a Labroides, it would be wise to house it in a larger tank with a relatively large fish community. In a large tank it will also be easier for potential clients to avoid the attentions of a cleaner wrasse.

A client fish that gets nipped by a cheating Labroides may retaliate by chasing it off. This behavior is commonly seen in the aquarium and can be problematic for the cleaner, as certain tankmates may persistently attack it anytime it comes near. On rare occasions, a exasperated fish may turn on the cleaner and kill it. For example, triggerfishes have been known to dispatch an annoying cleaner wrasse. On the other hand, Labroides will sometimes hound less maneuverable species, like puffers, trunkfishes, and porcupinefishes, causing them great duress. This pestering may even elicit an Ostracion trunkfish to emit its deadly toxins and wipe out a whole captive community. A confused cleaner might persistently attempt to nip at and chase fishes with small spots. In some cases, it appears that the cleaner is attempting to feed on the “parasite-like” markings.

Copyright (2008) Scott W. Michael

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