Rhadinocentrus rhombosomoides (Cairns Rainbowfish)

Family: Melanotaeniidae

Distribution: Cairns Rainbowfish live in the freshwater rivers between Cairns and Innisfail in Queensland, Australia. More specifically, the shallow, rocky creeks and small clear streams that drain into the Bellenden Ker range are home to this rare species. This species are now facing extinction and are on DPI&F Protected Species List making the collection of this fish and eggs prohibited.

PH: 7.0 -8.0

Temperature: 20°C -25°C (68 – 77F)

Hardness: 10-19dH

Description: The slim-bodied Cairns Rainbowfish is rather indistinct compared some of the other stunningly decorated rainbowfish family members. Nevertheless they are beautiful with their yellow-green and white bodies. They grow up to 8.5 cm (3.3 inches).

Diet: Rhadinocentrus Rhombosomoides are not picky eaters and will readily accept live, frozen and dried foods. Provide a varied, high quality diet for best health results.

Breeding: Most of the information we know about the spawning activity of Cairns Rainbowfish is based on aquarium observation, so it is evident that they can be bred in aquariums.

Feed your breeding fish with live food to get them into prime condition. Set up either java moss or artificial mops in your breeding tank, although it has been known for them to spawn in gravel substrate. After a week, the eggs will hatch and you should feed them on brine shrimp or similar. For a better chance at success, remove your fry to a separate tank to avoid predation.

Comments: Not commonly kept in the aquarium hobby because of its more modest colouration, the Cairns Rainbowfish has earned a reputation of being difficult to keep and only advisable for advanced aquarists with an interest in Australian native fish. Additionally, it is said that they do not travel or handle well.

The best chance of successfully keeping thriving Cairns Rainbowfish is to mimic its natural habitat. Stable water conditions, strong currents, sheltered hiding places, high oxygen content and a gravel or like substrate, is best suited. Aquatic vegetation is not necessary because they do not often occur in their natural environment. Provide an aquarium of at least 100cm (3 feet) for these energetic swimmers.

Tip: Collection of fish and eggs are prohibited so be sure you do your research before

you purchase this fish.

Given that they known to be peaceful and zippy fish, it would be advisable to house them with other similarly passive and active fish in a large community tank. A species tank could also work in order to best monitor their progress.