Bluestreak Cleaner Wrasse removing parasites from a Lamarck’s Angelfish.

The keeping of marine species is a relatively new hobby compared to keeping freshwater and avian species, even newer than keeping herptiles (reptiles and amphibians). And of course much newer than keeping warm blooded species such as dogs, cats, bunnies, horses, etc., some of which have been kept for hundreds of years.

Today, understanding the bio diversity of the vast oceans has become a very dynamic process. It involves discovery, interaction, and ultimately learning about an incredible large and diverse number of inhabitants. New information on the keeping of marine species is constantly evolving and becoming available as marine specialists, enthusiasts, and hobbyists learn more and more about the needs and requirements of individual species… and the marine environment as a whole.

The wrasse family “Labridae” is huge, with over 500 described species. The Cleaner Wrasses comprise just one of about 60 genera in this family. This is one of the most dynamic families, with new species of wrasse being discovered regularly and the habits and needs of many species being revised and revisited as more knowledge is gained.

The Cleaner Wrasses, of which there are five described species in the genus Labroides, are classified as obligatory feeders. This means they obtain all or virtually all of their nutrition by consuming parasites and other debris from the bodies, fins, and mouths of other fish. Just as their name describes, they are cleaner fish whose entire lifestyle consists of (and relies on) a symbiotic relationship with other fish.

The loss rate of captive specimens of Cleaner Wrasses has been astronomical with almost all cleaner wrasses dying within a few days to a few weeks, ultimately of starvation. Today, many marine biologists and other marine specialists study the cleaner wrasses intently, exploring their role in their environment and their impact on the marine ecosystem.

A few extremely dedicated enthusiasts have been willing to devote the time and means necessary to provide these fish with what they need to survive and thrive in captivity. However the success rate is minimal and such a specialized dedicated effort is beyond the interest and scope of the most marine hobbyists, even most advanced marine enthusiasts. Consequently, cleaner wrasses are generally considered not sustainable in the home marine aquarium.

common cleaner wrasse
Image Credit: SeraphP, Shutterstock

Cleaner Wrasses

Cleaner Wrasses in CaptivityConservation and the Cleaner Wrasses

Should cleaner wrasses be kept in captivity?

   Anyone considering keeping cleaner wrasses needs to consider their sustainability in a captive environment. The collective buying habits of hobbyist’s effect the market forces. This is a powerful voice that ultimately determines whether dealers stock a particular species or not.
   As author John H. Tullock remarks in his book, Natural Reef Aquariums: Simplified Approaches to Creating Living Saltwater Microcosms “…of more concern than mere removal is the fate of such species once collected”.
   And he points out that the economic voice of the hobbyist (deciding to buy this fish or not), “…is far preferable to attempts by government regulators to control the importation of aquarium species”.

Captive environments are explored below:
Home marine aquarium
Dedicated marine environment

In the marine home aquarium

   Cleaner Wrasses have a poor history of sustainability in the marine aquarium. Tens of thousands of these little fish have been captured for the ornamental fish industry. Out of those, there is just a sprinkling of reports describing any sort of success in keeping this fish alive.

  The problem of keeping them alive in the marine aquarium arises from their specialized feeding requirements:

  • They are obligatory feeders, eating primarily parasites, mucus, scales, and debris from other fish.
  • In the hobbyist’s marine aquarium this food is either not readily available, or not in sufficient quantities to sustain this obligate feeder.
  • Once the parasites have been exhausted, the vast majority of these fish die of a slow starvation.
  • Very few have been successfully encouraged to eat other foods.

   Today, due to the increased knowledge of their specialized requirements and the inability to sustain them in a captivity:

Not a Pet!
Cleaner wrasses
are not recommended for the average home
marine aquarium.

   Many marine experts confirm these problems, and do not recommend cleaner wrasses for home marine aquariums.

  • In his book, The Conscientious Marine Aquarist, author Robert M. Fenner says, “I have heard stories and seen the endemic Hawaiian Cleaner, L. phthirophagus accepting dry-prepared, freeze dried, fresh, and live foods, still wasting away and dying.”
  • Authors Dr. P. V Loiselle and Hans A. Baensch in their book Marine Aquarist Manual, state, “Labroides dimidiatus, L. bicolor and L. phthirophagus differ only in the rapidity with which they starve to death in captivity.” Additionally they describe that to escape starvation cleaner wrasses begin harassing their tank mates, “…slow starvation translate to incessant solicitation of their companions that drives both their intended clients and their keepers to complete distraction”.

In dedicated marine environments

   On a brighter note, though these fish are extremely difficult to keep in the average marine aquarium there are scientists, public and commercial organizations, and a few individuals that have reportedly sustained these fish.

  • Researchers have sustained these wrasses in a controlled setting.
    This report, The secret appetite of cleaner wrasses states, “Grutter and Redouan Bshary of Cambridge University in England administered a taste test. They trained the cleaner wrasses (Labroides dimidiatus) to eat off underwater trays and then offered an array of parasites and fish-mucus samples.”
  • Cleaner wrasses have been used successfully in public aquariams and in aquatic commercial farming.
       Japanese researchers T. Shigeta, H. Usuki, and K.Gushima in their report Interaction Between Cleaner and Host: etal, state that, “There has been little study on the behavior of fishes in the sea around Japan, except for the cleaning wrasse Labroides dimidiatus which is often used to control ectoparasites on fish exhibited in aquariums.
       In his abstract, A review of potential pathogens of sea lice and the application of cleaner fish in biological control, J. W. Treasurer reports, “Cleaner wrasse (Labridae) have been stocked commercially with farmed salmon since 1989, and recent work on improving the method is reviewed. Wrasse are source from a wild fishery and stocked at ratios of 1 to 25-150 salmon.” This report does not indicate the mortality rate of the cleaners, but does go on to say, ” Health hygiene includes… vaccination of wrasse and ultimately rearing wrasse for stocking.”
  • And finally, one marine enthusiast’s success.
    Ray describes, in his article “Raising Cleaner Wrasse“, his approach and resulting success in keeping the Bluestreak Cleaner Wrasse, L. dimidiatusis.

Is the collection of cleaner wrasses from the oceans a conservation concern?

   With cleaner wrasses being removed from their natural environments, conservation concerns have arisen involving the impact on reefs and reef fishes, primarily in these two areas:

  1. Threatened or Endangered status:
    Are the cleaner wrasses becoming threatened or endangered with removal, and are the populations diminishing?
  2. Reef diversity and the health of reef fish:
    What is the impact of removing cleaner wrasses on the diversity of species on the reef, and the impact on the health of the other reef species?

   There have been various studies done in these areas,
but they have produced disparate results.

Threatened or Endangered Status:
  • None of the cleaner wrasse species are listed as endanger by CITES (Convention on International Trade in Endangered Species)
  • Nor are they listed on the IUCN (International Union for Conservation of Nature and Natural Resources) red list of threatened species.

   The Bicolor Cleaner Wrasse L. bicolor has been declared protected by IUNC Sri Lanka, which states “Populations of the Bicolor Cleaner Wrasse are naturally low in Sri Lankan waters, and are further threatened by degradation of reef habitats and collection for the ornamental fish trade. Therefore, it is now declared as a protected species under the Fauna and Flora Protection Ordinance.”
   Also in his book The Conscientious Marine Aquarist, Robert M. Fenner tells us that in 1996 Hawaii banned the collection of its endemic Hawaiian Cleaner Wrasse L. phthirophagus.

Reef diversity and the health of reef fish:
Current view:
Cleaners provide diversity and maintain the health of other fish
   The current view is that the cleaner wrasses play a prime role in the reefs they occupy, effecting the diversity of other fish on the reef as well as the health of these fish. Thus removal of cleaner wrasses could have a negative effect.
  • In his 2003 study at Ras Mohammed National Park, Egypt, The cleaner wrasse, Labroides dimidiatus, is a key organism for reef fish diversity at Ras Mohammed National Park, Egypt, Redouan Bshary writes that the disappearance or removal of cleaner fish at this reef “had no immediate effects on fish abundance, i.e. within the first few weeks. A significant decline in fish diversity was only detectable after 4–20 months. In contrast, cleaner immigration or experimental addition led to a significant increase in fish diversity within the first few weeks.” He states , “This study demonstrates that cleaner fish are a key organism for local reef fish diversity.”
  • Highlights of an 18-month study on Lizard Island in 2003 by Dr. Lexa Grutter and her team from the University of Queensland, Australia say, “…cleaner fish have major effects on individual fish activity patterns and indirectly on demography,…” and also this, “…findings argue for a functionally significant role of cleaner fish on the composition of reef fish species”.

Alternate view:
The symbiotic relationship of cleaners and their clients may be one of ‘mutualism‘, a beneficial relationship more than a required relationship:
   There are several studies indicating that health of host fish may not be devastated by removal of the wrasse, though there are definitely less parasites on fish that are cleaned. It is also indicated that rather than this being a required relationship between the wrasse and his host, this may be more of a mutualistic relationship.

  • An often cited earlier study (Limbaugh, 1961), found that fish became diseased when cleaners were removed from a reef. However Alexandra S. Grutter (1997), in her report Effect of the removal of cleaner Fish on the abundance and species composition of reef writes, ” …Limbaugh (1961) admitted his ‘experiment was a gross one and not well controlled’.” She goes on to say, “The removal of cleaner fish from reefs had no detectable effect on fish abundance or species composition. This indicates that client fish did not suffer increased mortality in the absence of cleaners and/or fish did not leave reefs to seek cleaning elsewhere. The findings agree with all other similar quantitative cleaner fish removal experiments (Youngbluth 1968; Gorlick et al. 1987; Grutter 1996b).
  • Another report The ultimate effect of being cleaned: does ectoparasite removal have reproductive consequences for damselfish clients? by  Karen L. Cheney and Isabelle M. Côté follows the same line as Grutter’s above, going on to say, “The long-held belief that cleaning interactions among fish are mutualistic …subsequent studies failed to find any effect of cleaner absence on client health or abundance… Furthermore, there is ample evidence that cleaners often take not only ectoparasites but also scales and mucus from their clients.” They also report that cleaners do remove ectoparasites and that these parasites do damage the clients, but that “Such ultimate consequences (enhanced survival or reproduction) of being cleaned have not yet been examined.”

Other views:
Many new findings (beyond the focus of the study itself) often suggest themselves, which then need their own study.

   Multiple variables come into play when studying these fish and their clients in their ocean environment. These variables contribute to disparate results between studies, as well as suggesting new results and more questions. Each study is focused on a particular aspect of the wrasse or its environment. From each study a variety of conclusions suggest themselves. They are often unrelated to the focus of the study itself, and often need a separate study to substantiate them.

For example:

  • The study focus might be: Does the presence of cleaner wrasses on a reef keep other fish healthy?
  • The result might conclude: The health of resident fish were not significantly affected by the wrasse presence, but the number of migratory fish traveling between the reefs is less.
  • So a new (unrelated?) result: Wrasses are significant to the diversity of fish on the reef.

   The work of scientists researching ocean life is extremely complex. They are constantly uncovering unexpected results with a whole new set of variables that need to be addressed.

   Although studies are not conclusive as to what the actual effect of the removal or addition of the cleaner wrasses on reefs will be, some suggest that the quantity and types of fish may vary depending upon how many cleaners are available. Some fish seem to migrate out of areas with fewer cleaner wrasses, and migrate into areas with more.

   It is known that lots of cleaners = more fish and more diversity in types of fish. Scientists like to set up observation points where there are lots of cleaners as it gives them a greater diversity of fish to observe.



Featured Image Credit: Aleron Val, Shutterstock