The introduction of Labroides spp. cleaner wrasses to marine aquarium systems is generally ill-advised. Though some hobbyists report success in keeping these obligate cleaners long term, the vast majority of specimens entering the market are doomed to perish prematurely from starvation. Nonetheless, despite their abysmal captive survival rate, people continue to buy these wrasses, likely owing to some persistent misconceptions surrounding them.
Among these myths are:
1. If the wrasse can’t get enough to eat by cleaning, it will learn to accept other foods
First off, there’s no if about it—a cleaner wrasse kept in a home aquarium cannot sustain itself long term by cleaning its tankmates. After all, in your average home system, there are going to be very few clients to service and they likely won’t have much of a parasite load or dead tissue to offer. So, if the wrasse doesn’t learn to recognize aquarium fare as edible, it’s destined to starve. Trouble is, it’s the exception, not the rule, when a specimen learns to accept substitute foods. Even among those that do accept alternative foods, many specimens still waste away and perish.
2. They’re a good natural alternative for treating a marine ich outbreak
Labroides wrasses do pick certain ectoparasites off fish, but Cryptocaryon irritans isn’t one of them. Even if it were, these wrasses couldn’t make any headway against the infective trophont stage of the parasite. At this point in its lifecycle, the ich parasite isn’t clambering over the surface of the fish’s body as one might imagine. Rather, it actually penetrates beneath the skin where it can feed with impunity and cannot be reached by cleaner organisms.
3. They’re immune to marine ich
When introducing a Labroides wrasse to a marine aquarium in hopes of eradicating ich, you’ll likely just end up with another infected fish. Contrary to popular misconception, cleaner wrasses have no special immunity to Cryptocaryon irritans or other diseases.
4. Fish always appreciate a good cleaning
We all enjoy a good massage now and then, but how would you feel if you had a masseuse or masseur chasing you around all day, every day, trying to lay hands on you? More stressed out than relaxed, right? The same applies to cleaner wrasses and their client fish. On the natural coral reefs, fish seek out cleaner services on an as-needed basis, but not so in an aquarium where they’re very literally a captive audience. In this situation, the cleaner’s incessant attention—which is distributed over a relatively small number of specimens that can’t swim away—can become a major source of stress and irritation.
5. Cleaners are always safe around predators
Admittedly, this last myth is an issue only if you attempt to keep a cleaner wrasse and a larger predator together in the same tank, but it’s worth noting nonetheless.
After observing a cleaner wrasse attending to a large predatory species, such as a grouper or moray eel, with no harm done, one might be tempted to assume the same truce will hold in captivity. Unfortunately, that’s not always the case.
Again, you have to keep in mind that the cleaner/client relationship in the wild is a temporary one. A predatory fish requiring cleaning services will approach a cleaner organism at a particular station on the reef, signal through body language that it “comes in peace,” allow itself to be cleaned, and then move on. Combine these same two animals on a permanent basis, however, and it’s always possible that the larger species’ predatory instincts will at some point override its usual forbearance.