Court Jester Goby (Koumansetta rainfordi)
The Court Jester Goby (Koumansetta rainfordi) known to tropical fish keeping enthusiasts as Rainford’s Goby or Old Glory Goby is found in the Western Pacific .
Koumansetta rainfordi‘s range extends from the southern Great Barrier Reef in Australia to Tonga; north to Taiwan and the Philippines, and throughout Indonesia, Papua New Guinea, the Marshall Islands, Solomon Islands, and Fiji.
The Court Jester Goby is a solitary, somewhat social species that is most frequently encountered hovering over the sandy sea bottoms and mud flats of the coral reefs of their range, alone or in small groups, at depths from 6 to over 98 feet, where they forage on benthic algae, copepods, and tiny invertebrates.
Court Jester Goby (Koumansetta rainfordi)
Rainford’s Goby has a compressed, elongated, vibrant olive green to charcoal gray colored body, with five dark blue edged bright orange to red horizontal stripes, and a row of white spots on the upper back. There is a yellow edged black spot on the second dorsal fin and a black spot on the upper base of the caudal fin.
The Court Jester Goby is a timid, peaceful species that can be housed alone in a mature FOWLR or Nano reef tank of at least 20 gallon capacity, or in small groups in larger aquariums of 100 gallons or more with a live sand substrate and plenty of live rock arranged into caves, crevices, and overhangs for them to hide among.
As long as they don’t have to share a small tank with their own kind, Koumansetta rainfordi are rarely aggressive to other species. Avoid keeping them with hawkfish and dottybacks.
The Court Jester Goby ignores corals, is completely reef safe, and will quickly clean up any pesky hair algae in a reef aquarium. In fact, many wild caught specimens seem to want nothing but hair algae in their diet and have starved to death without substantial amounts in the tank.
The good news is that modern tropical fish keeping enthusiasts have live copepods readily available to keep wild caught specimens healthy. Additionally, aquacultured specimens that are less finicky about their diet, hardier, and even more social are readily available from a variety of retailers.
The Court Jester Goby can spawn in an aquarium environment but rearing the fry is extremely difficult.
In their natural habitat, the Court Jester Goby feeds on filamentous algae and small crustaceans. In a mature aquarium with plenty of live sand, live rock and algae for them to graze on their diet should consist of filamentous algae, live and frozen brine shrimp, chopped krill, finely chopped squid, Mysis shrimp, frozen herbivore foods, etc.
The Court Jester Goby (Koumansetta rainfordi) is available to tropical fish keeping enthusiasts as wild caught or captive bred specimens from a variety of online retailers, wholesalers, and transhippers at prices that vary by size and area of collection.
Approximate purchase sizes are: Small: 3/4″ to 1″; Medium: over 1″ to 2″; Large: to 3″. Prices range from $29.99 for small Coral Sea specimens to $45.99 or more for large Indonesian specimens.
Court Jester Goby (Koumansetta rainfordi)
Minimum Tank Size: 20 gallon (100+ gallons for pairs)
Aquarium Type: Reef or FOWLR
Care Level: Moderate
Temperament: Peaceful
Aquarium Hardiness: Hardy
Water Conditions: 72-78°F, dKH 8 – 12°, pH 8.1–8.4, sg 1.020-1.025
Max size: 3″
Color Form: Blue, Green, Orange
Diet: Omnivore
Compatibility: Reef Safe
Origin: Coral Sea, Indo-Pacific, Fiji
Family: Gobiidae
Lifespan: 5 – 7 years
Aquarist Experience Level: Intermediate
