Practical Fishkeeping (UK)
Cleaner wrasses are the dermatologists, beauticians and masseuses of the reef. But are they really suitable for captive care? We look at the arguments for and against keeping these remarkable fish in a mixed aquarium.
is curator at the Blue Planet Aquarium in Cheshire Oaks. He looks at the arguments for and against keeping Cleaner wrasse.
Cleaner wrasses offer an important service to other fish in the wild, including removing dead skin and picking off isopods, flukes and various other ectoparasites, all to the greater good of the reef.
In the aquarium they can provide clear benefits, but in the wrong system they are a poor choice due to their challenging nature. Having said that, the appearance of captive-bred specimens means that we may be looking at sustainable and much less demanding animals in the future.
The Bluestreak cleaner wrasse
The Bluestreak, Labroides dimidiatus, is probably the definitive cleaner wrasse for most aquarists. Widespread around the Indo-pacific, it reaches around 10cm/4in in length and sports a distinctive ‘cleaner blue’ colour. On the reef, L. dimidiatus is territorial, and pairs or groups establish cleaning stations which are visited by client fish for removal of parasites, loose and damaged scales, and dead skin. Providing a good service means repeat business with clients returning to their preferred cleaner.
The Bluestreak cleaner is by far the most commonly-offered species and the least difficult to care for — but that’s relatively speaking; it still presents challenges. While it can be trained to accept prepared foods, these should only be viewed as supplementary, and the wrasse’s appetite for cleaning can create issues.
A study by Alexandra Grutter of James Cook University in Queensland revealed that Bluestreaks are prodigious cleaners, consuming around five parasites per minute and dealing with over 2000 client visits per day! And cleaner wrasses don’t just feed on parasites: they will ‘cheat’ by preferentially feeding on fish mucus and skin, as this gives a nutritional boost (at a cost to the client). On the reef, they tend to do this if they can get away with it, so they appear to cheat herbivorous clients rather than predators capable of eating them. They will also tend to cheat more frequently when parasite loadings are low within their client base.
What this means is that the system must be right for these wrasses to thrive. They can be brilliant in large systems with sufficient numbers of client fish. Given enough space, it’s possible for one or two wrasses to establish a cleaning station which their clients can visit when they wish (and escape if they need to) — and if the tank is suitably stocked, the cleaners won’t tend to focus their attention on a small number of clients.
Put them in a small tank with just a few fish, however, and they can be a pest, constantly harassing their tank mates and damaging them through their incessant pecking. Ideally, you’re looking at a system of 1000 l or more, jam-packed with fish.
We all know that a massage is a great way to de-stress. Cleaner wrasses often engage in pre-cleaning ‘massages’ by rubbing clients with their pectoral and pelvic fins. This tactile stimulation appears to be beneficial to the client fish. Presumably it helps build up trust between cleaner and client, but it also appears to reduce stress levels in the client. This was demonstrated in an ingenious 2011 study* by Marta Soares and her collaborators.
Two types of model cleaner wrasses were made separately available to Silver spot tangs, Ctenochaetus striatus. Both models were identical — each type was painted to resemble a Bluestreak cleaner wrasse and had soft bristles — where the differences lay was that one was moving courtesy of a mechanical rocker;
the other type was stationary.
The tangs with the moving models spent much more time with them than those with the stationary ones; this included posing, touching and physically interacting with the models. Soares then examined the stress responses of the tangs by measurement of the hormone cortisol, including confined (stressed) and non-confined (nonstressed) fish. The results revealed that tangs which interacted with the moving models had lower cortisol levels (and therefore lower stress responses) than those with access to stationary models. Not only that, when subjected to confinement in a bucket, fish which had previously interacted with a moving model demonstrated a lower stress response.
The study provides strong evidence that direct physical contact of the kind provided by cleaner wrasses is beneficial for reef fish (Soares suggests that the massages are offered as a trade-off by the cleaner to offset the effects of cheating). Whatever the reason, it seems that the massages provide a tangible benefit to their tank mates in the form of reduced stress. It’s possible that adding a cleaner to the aquarium could provide the same benefit, but this needs to be balanced against whether they have a choice to interact with the cleaner or not.
Hawaiian cleaner wrasse
The Hawaiian cleaner wrasse, Labroides phthirophagus, is a gorgeous species, with its golden anterior half and bright violet tail markings. It reaches around 10cm/4in in length and is endemic to the Hawaiian region. In the wild, this is an obligate cleaner, relying on a diet of parasites and fish mucus; without suitable numbers of clients in the aquarium, it is very difficult to maintain. Although wild-caught L. phthirophagus are very challenging fish, in 2016 Avier Montalvo bred the species at Rising Tide Conservation in Hawaii. This was initially unintended, when a pair of the wrasses spawned in a system housing broodstock including tangs and butterflies. Avier has now bred the species twice, and his experiences suggests that if the fish are raised on prepared diets they can effectively be conditioned to become facultative cleaners (meaning they don’t rely on cleaning alone to meet their nutritional needs), making them potentially more suitable for aquaria. This is game-changing stuff. The implications for conservation are obvious, but it also illustrates how culturing such challenging species can address many of the difficulties associated with their long-term care. Nobody’s suggesting that captive bred Hawaiian cleaner wrasses are suddenly ‘beginner’ fish, but they certainly look more viable for aquarium life. While we aren’t at the stage where captive-bred cleaner wrasses outnumber their wild-caught counterparts in the trade, Rising Tide’s Hawaiians have been made available to North American hobbyists through Los Angelesbased Quality Marine. This is one of many Rising Tide breeding projects the company supports, with an impressive list of species which includes the Milletseed butterflyfish, Chaetodon miliaris; Regal tang, Paracanthurus hepatus; Melanurus wrasse, Halichoeres melanurus; Yellow tang, Zebrasoma flavescens, and the Yasha goby, Stonogobiops yasha.
Has the feedback been positive regarding the captive bred cleaners? “Quality Marine Account Managers have received nothing but great feedback from the customers that purchased the captive bred cleaner wrasse, which I think made this project even more successful,” Cynthia Delillo of Quality Marine explains. “Traditionally, this species has been considered sensitive and challenging, and especially difficult to feed properly. Rising Tide’s captive bred ones are reared on readily available diets, and don’t have these same feeding issues, which was very attractive to our customers.”
Cynthia feels that aquaculture will play a deciding role in the future of the hobby — and ultimately, of the oceans themselves, but price appears to be a barrier at the moment. “The increased costs associated with culturing these species typically results in a more expensive animal, which is not always accepted by hobbyists,” she says. “I do believe that price will greatly determine the future of aquaculture. Everyone in the industry needs to work together to better educate the public on the importance of aquacultured marine ornamentals and why they should choose a cultured specimen.”
Bluestreak cleaners have previously been cultured by Bali Aquarich with impressive results, and Rising Tide’s successful breeding of Labroides phthirophagus ups the ante considerably. It does seem that captive breeding is the way ahead here. Not only could we have fish that are easier to keep, but we can be confident that they are ethically sourced. There are concerns that removing cleaner wrasses from the wild may impact on the health of fish on the reef; combine this with the generally poor survival rates of wild-caught cleaners in aquaria, and it’s not a good look for the hobby. The know-how is there to breed them, so we can have them if we want them badly enough — and, crucially, are willing to pay a premium for the privilege.
Although the prospect of cultured specimens will make them more accessible, many systems just won’t be suitable for a cleaner wrasse. No cleaner is ever going to be a ‘magic bullet’ to eradicate disease from the aquarium, but there are less challenging alternatives to cleaner wrasses that also offer ‘personal services’ on the reef.
Of the numerous cleaner shrimp species, the Scarlet cleaner shrimp, Lysmata
amboinensis, from the Indo-pacific is hard to beat. Reaching around 6cm/2.2in in length, with its red, white and gold stripes and distinctive white antennae, it’s very attractive. This is by no means an obligate cleaner (and it also makes a great scavenger), but given the opportunity it will happily primp and preen fishy clients. They can be kept in pairs in small tanks (and groups in larger systems), and while raising the young is a challenge, they can be captive bred. Be cautious if housing them with large crustacean-munching fish such as puffers and triggers, as they may find the shrimp too good to resist, particularly during moulting. As with all shrimp, acclimate extremely slowly to prevent salinity shock. The Atlantic cleaner gobies of the genus
Elacatinus are also an excellent alternative. The tiny 5cm/2in Neon goby, E. oceanops, from the Caribbean, is arguably the go-to species. It can be kept in pairs in tanks of less than 100 l, or in groups in larger set-ups, and can be captive bred, too. They don’t rely on a diet of parasites to survive and happily accept a variety of prepared foods, but will set up a station and perform cleaning duties if kept with other fish. Take care in tanks with predatory fish or larger crustaceans.
FURTHER READING *Soares, M.C. et al. (2011) Tactile stimulation lowers stress in fish. Nature Communications. 2:534