There are a number of marine organisms that make almost all of their living by cleaning parasites off of other fish. This includes a number of shrimp that pick larval isopods off piscine neighbors and a group of wrasses that service hundreds of clients a day. Then there are the cleaner gobies, the most active cleaners along the coasts of the Americas. The cleaner goby most often encountered by aquarium hobbyists is the neon goby (Elacatinus oceanops). This diminutive fish is an even better cleaner species for the home aquarium than its labrid counterpart, the bluestreak cleaner wrasse (Labroides dimidiatus). It tends to be hardier and is not as annoying to other fish as Labroides dimidiatus (the latter species tends to be more aggressive in its cleaning technique). Its list of clients is long and can include small damsels to the large and imposing greater barracuda. When a fish is ready to be cleaned, the neon goby will leap on to its patron and begin looking for the crustacean parasites to harvest. This may mean entering the mouth or the gills of its client. When the larger fish is ready to move on, the simply shakes off the gobies. The neon goby has been known to clean more than 100 client fish per hour!
Difficulty: The neon goby is a very easy fish to keep. It is plain and simple —avoid keeping the neon goby with fish species that will eat it, then it should do well in most home aquarium community aquariums. Fortunately, the neon goby will readily eat most aquarium foods, although particle size will need to be small so that this little fish can ingest it. Frozen fish eggs, finely grated frozen seafood and frozen Cyclops are all good foods for the neon goby.
Physical description: The neon goby is black on the back and sides, white on the belly and has two bright blue racing stripes down the sides. The neon goby reaches about 2 inches in length.
Range: The neon goby sets up shop at a specific location on the reef. This is often a stony coral promontory or a sponge that is home to one or a pair of these fish. This cleaning station will be visited by its piscine customers — in some cases these are individual clients, but in other cases shoals of fish will swarm the cleaning site. Not all of the members of the genus Elacatinus are cleaners. Some are always found in association with tube sponges, living within the chimneylike lumens.
Compatibility: The neon goby is not aggressive toward non-related species. The neon goby can be kept in pairs, but it is important to obtain a male and female. The easiest way to do this is to place a group of juveniles together and watch them interact. If you see two fish getting along well together, separate them out from the rest of the bunch and keep them together. Adults can be very aggressive. If you place a neon goby pair together and they are not a heterosexual pair, the dominant fish will usually chase the other goby around until the subordinate fish dies. The neon goby is sometimes attacked by bellicose species that live near the substrate. Some of the worst offenders belong to the family Pseudochromidae, the dottybacks. Other fish that may chase or nip at the neon goby include hawkfish, wrasses (e.g., hogfish, Bodianus; lined wrasses, Pseudocheilinus) and sandperches. Cleaner species are often not eaten by predators due to the services they provide. But their cleaning reputation, as well as distasteful body slime, does not dissuade some predators (e.g., frogfish, scorpionfish, hamlets, wrasses in the genus Thalassoma) from slurping them up. The neon goby has been known to nip at clam mantles on occasion but does so less frequently than the bluestreak cleaner wrasse.
Aquarium conditions: Acceptable water parameters for the neon goby are: pH of 8.1 to 8.4, specific gravity of 1.019 to 1.025 and a water temperature of 76 to 82 degrees Fahrenheit.
Care considerations: The neon goby can be housed in aquariums as small as 5 gallons to the largest reef aquarium. While the neon goby is not likely to prevent parasites from finding their way on to your aquarium fish, it may help reduce the numbers of certain types (e.g., Cryptocaryon). Unlike the cleaner wrasses, the neon goby will not chase clients around the aquarium and harass them (they employ a less aggressive type of parasite-picking).
Breeding: The neon goby will spawn in the home aquarium, and captive-bred and raised individuals are often available to aquarists. The neon goby lays its eggs in holes or caves in the rockwork. When the eggs hatch, the larger larvae can be raised on rotifers.