Cleaner fish
[2] This example of cleaning symbiosis represents mutualism and cooperation behaviour,[3] an ecological interaction that benefits both parties involved.
The client animals are typically fish of a different species,[3] but can also be aquatic reptiles (sea turtles and marine iguana), mammals (manatees and whales), or octopuses.
[5][6][7] A wide variety of fish including wrasse, cichlids, catfish, pipefish, lumpsuckers, and gobies display cleaning behaviors across the globe in fresh, brackish, and marine waters but specifically concentrated in the tropics due to high parasite density.
[1] Cleaning behaviour takes place in pelagic waters as well as designated locations called cleaner stations.
[3] Conspicuous coloration is a method used by some cleaner fish, where they often display a brilliant blue stripe that spans the length of the body.
The specialized feeding behaviour of cleaner fish has become a valuable resource in salmon aquaculture in Atlantic Canada, Scotland, Iceland and Norway[10] for prevention of sea lice outbreaks[2] which benefits the economy and environment by minimizing the use of chemical delousers.
Lumpfish are utilized as salmonid cleaner fish in aquaculture, but it is unknown if they display cleaning behaviour on salmon in the wild.
[1] Facultative cleaners may display cleaning behaviour through their whole life history or solely as juveniles for additional nutrients during rapid growth.
Using the example of the blue wrasse from Caribbean waters, their alternative feeding strategy is described as being a generalist forager, meaning they eat a wide variety of smaller aquatic organisms based on availability.
[19] An example of an obligate cleaner is the shark nose goby (Elacatinus evelynae) in the Caribbean Reef, where it has been observed to perform up to 110 cleanings per day.
This can be harmful to the client as mucus is essential to prevent UV damage, and open wounds can increase the risk of infection.
[2] Cleaner fish maintain a balance between eating ectoparasites and mucus or tissue because of the respective nutritional benefits, sometimes despite the risk to the client.
[4] For example, the Caribbean cleaning goby (Elacatinus evelynae) will eat scales and mucus from the host during times of ectoparasite scarcity to supplement its diet.
The symbiosis relationship between client and host does not break down because the abundance of these parasites varies significantly seasonally and spatially, and the overall benefit to the larger fish outweighs any cheating on by the smaller cleaner.
[3] It has also been observed that obligate cleaners have higher overall brain activity, and specifically in the cerebellum, likely related to the movements involved in cleaning.
[21] One of the most studied examples of mimicry on coral reefs is the relationship between the aggressive mimic Plagiotremus rhinorhynchos (the bluestriped fangblenny) and the cleaner wrasse model Labroides dimidiatus.
[13][11] Sea cages are designed with additional substrate for lumpfish to attach to during periods of inactivity to minimize stress levels in the cleaner fish and maximize delousing abilities.
[2] Sea lice outbreaks are detrimental to the survival of cultured salmonids and cause the majority of revenue loss in the aquaculture business.
By employing the cleaner fish instead of medical intervention for sea louse management, aquaculture farmers save money.
