I would imagine that all marine aquarists have heard of, and probably seen, the cleaner shrimp (Lysmata amboinensis). This colourful shrimp is very popular, becoming used to the aquarist very quickly and even walking around on the hand if the opportunity presents itself – a large and strangely shaped fish to be cleaned perhaps.
There is another creature known for the natural cleaning activities it undertakes. This is the cleaner wrasse (Labroides dimidiatus). The fish is commonly known as the cleaner wrasse or blue streak wrasse. There are other reef fish that undertake cleaning duties particularly when juvenile, but this wrasse does it as a full time job.
The wrasse likes to go into a small hole or crevice for security when night arrives. During the day, it seldom moves far from the area, as it is a cleaning station. In other words, the little wrasse, usually in a group, wait for other fish to come so that they can be cleared of parasites and other irritants. The wrasse goes busily about the fish being cleaned, as this is the food source. They will even enter the mouths and gills of bigger fish, including predators – the larger fish normally hang still, fins spread when being cleaned, and keep their mouths open to allow easy access. The cleaner wrasse are protected from predation during this activity possibly by their swimming motion, colours, shape, or all three. The cleaner stations are well known to other reef inhabitants, and it is known for fish to wait and queue patiently for attention. There are always enough fish for cleaning, and thus food for the wrasse.
As with many wrasse, the cleaner is hardy in a good aquarium environment. It needs plenty of swimming space and places to hide. The normal caution should be exercised with regard to health when purchasing one.
On the wild reef there are plenty of fish to be cleaned, but not so in the aquarium. Even in a fish only system where there are normally more fish per gallon, there is insufficient natural food. It follows that this will be the same in a reef system. Also of course, the last thing the aquarist wants is parasites in the aquarium. Talking of parasites, it might be thought that the wrasse could be of use in a fight against marine white spot or velvet. Unfortunately, this is reportedly not the case and the wrasse is vulnerable to the parasites as well.
When considering introducing a cleaner wrasse to the aquarium, the usual compatibility question applies, though this is not usually a problem from the wrasse‘s point of view. When the wrasse is in the aquarium, natural instincts continue. It may ‘think’ that the fish in the area are waiting for cleaning and attempt to carry out this task. These attempts can continue over and over again, day after day, and other fish can be highly irritated by the attention. The wrasse may be repeatedly warned off, though it is unlikely to be attacked, though if the system is a fish only with predators there could be a problem. Some predators, such as lionfish, may not have very good manners! It is said that if the wrasse ‘learns’ when food is available and responds to it with the other fish, the cleaning drive could diminish, as the driving force, hunger, is reduced.
As with other fish it is a good idea to ask a retailer to put a little food in the aquarium and watch the response of the wrasse. Many wrasse are easy to feed, generally being gluttons, and the cleaner type is reported to feed well too. There have been reports of starved cleaners that perished, but this does not appear to be the norm.
The food fed needs to have a little resemblance to that in the wild. Fortunately, most other fish will take it as well. Try frozen foods that are prepared for marines, such as mysis shrimp, artemia, shellfish, squid, lobster eggs and the like. Some may need to be chopped so that the cleaner can handle them. It is reported that the fish will often take flake food. A diet with plenty of variety, plus flake if possible, should be successful. Fed carefully, the seawater conditions should not deteriorate as other fish present will eat the same diet.
On the wild reef mimicry is not unknown, and so it is with the cleaner wrasse. Other fish trust the wrasse and do not hesitate to present themselves for cleaning. Taking advantage of this is a fish which is closely coloured and patterned. This is the false cleaner (Aspidontus taeniatus), which in fact is a blenny. What it does is present itself to a fish which is ready for cleaning, but instead of being useful it quickly bites a bit of fin or scale and dashes off. Not the way to win fishy friends! It is unlikely to be obtained in mistake for a proper cleaner, but the two are easily identifiable, the proper cleaner has a mouth at the front of the fish, the false one has an underslung mouth.
There are other cleaner wrasse, but none are reported to take to aquarium food as readily (I’d better avoid the word ‘easily‘) as the one discussed.