Reef Fish Profile: Blue Streak Reef Cleaner Wrasse
We have had this cleaner wrasse in our tanks for years and it never ceases to amaze with its acrobatic cleaning skills. Their constant activity have made them a favorite among many reef aquarists over the years including our team here at ReefNation. While these fish make a stunning visual addition to a reef tank, some recent studies are starting to show that their removal from the wild has drastic effects on the fish populations of that reef. Let’s take a closer look at the reef cleaner wrasse and what its importance is to reef communities in the wild.
Cleaner Wrasse: Labroides Family
The cleaner wrasse that we commonly see in the aquarium hobby is potentially one of a few species in the family Labroides. The range of the Labroides species is throughout the reefs of the Pacific Ocean. They go by the common name “cleaner wrasse” or “blue streak wrasse” when you see them in local fish stores or in aquarium books. Most often, these names are describing one species, Labroides dimidiatus which is common to reef aquarists around the world. They are sexually dimorphic little creatures which makes them able to switch between male and female as their environment requires. They also possess the classic wrasse feature of a protractile mouth which means that their teeth protrude ahead of their jaw, making them good “pickers” of food from rocks and small places. These fish are best known for the picking behavior they display almost 24/7 on many of the reef fish they live around.
Usually seen as a blue fish with a black stripe running down their center line, they can be seen picking at the bodies, mouths, and gills of their local reef cohabitants. One would think that being picked at on your face, mouth, and gills would be enough to chase any fish away. What we see though is quite to the contrary. It appears that just about every fish on the reef will in fact form a line to have this peculiar behavior performed on them. In our tanks, we have seen fish extend fins and flare gills in an attempt to get the cleaner wrasses’ attention. I guess if we didn’t have arms and couldn’t talk, we would use anything we could to tell someone scratching our backs exactly where the itch was!
Do Cleaner Wrasse Really Clean?
There has been much debate over the years as to what this behavior actually does for both the cleaner and the cleanee. I remember reading a study a few years ago that discussed whether or not these
cleaner fish were actually picking off any parasites, ich, or the like. They found in fact that the stomachs of these little guys didn’t in fact contain any parasites at all. This conclusion does seem pretty odd if you have ever seen a fish getting cleaned like this as they both look like they are totally digging it! In other studies, they have found some ecto-parasites as well as both live and dead tissues in the stomach content, suggesting that it was picked off during cleaning. Perhaps there is something to the whole ‘back scratching” observation after all? It also appears they may take advantage of the host fish letting its guard down and pick off live tissue in addition to the dead in order to sustain their nutrition.
Cleaner Wrasse: Tiny Part Of a Big Ecosystem?
The cleaner wrasse is a tiny little fish typically only up to 3-4″, but how does it fit into the larger reef ecosystem? Even though their size is small, the fact that these wrasse interact with most of the fish on the reef in some capacity leads to the conclusion that their role there must be pretty important whatever the particulars of it turn out to be. The findings of a study released in July came to just such a conclusion. In this study, cleaner wrasse on certain patch reefs were removed for a period of 8.5 years. All other factors being left alone, the results of this removal were quite shocking on the local reef environments. In areas where cleaner wrasse were removed, the number, size, and diversity of ALL the reef fish there decreased. Specifically, the following was observed: After 8.5 years, the two removal reefs differed from the control reef in the following ways:
- Damselfish (Pomacentridae) were smaller in size
- Resident fishes were 37% less abundant
- There was 23% less species richness per removal reef.
- The removal reefs also showed a staggering 65% reduction in juvenile visitor fishes (fish likely to move between reefs)
- There was 33% lower species richness of visitor fishes …
- and 66% lower abundance of visitor herbivores such as Tangs (Acanthuridae)
Next time you are at your local pet shop, aquarium, or diving on a reef, be on the lookout for these little guys and check out their interesting behaviors. Given the recent information regarding their importance to a reefs’ ecosystem though, we have to also say that these fish should be best observed in their natural environments and NOT kept in captivity. Their recently uncovered importance in the wild and the fact that they are difficult to nourish in captivity, lead to the conclusion that they are best left in the wild to play their important role in local reef ecosystems. Seeing them when you dive or snorkel is much more fulfilling and responsible than having them starve in your reef tank.