The Goyder River Rainbowfish (Melanotaenia trifasciata)
The unique fish fauna of Australia is something we seldom see in the aquarium trade, and, of the roughly 300 species of freshwater fish native to this region, no more than a handful are available to aquarists with any regularity. Of these, perhaps the most beautiful is a prismatic piscine hailing from the Northern Territory—the Goyder River Rainbowfish.
Rainbowfishes are one of the most recommendable groups of fishes for the freshwater community aquarium, being hearty and easy to care for, small and colorful in appearance, and peaceful in disposition. Australia and the nearby island of New Guinea are the epicenter of rainbowfish diversity, with each river system tending to have its own unique species, subspecies or variation. The population from the Goyder River is one of several visually distinct varieties of the widespread species Melanotaenia trifasciata. Elsewhere in its range (which includes the northern-most portions of Queensland and the Northern Territory), this fish comes in either a pale blue or orange coloration, with a relatively weak black stripe along the side, but, for the population form the Goyder, the body takes on a brilliant red hue and the black stripe intensifies to form a beautifully contrasting pattern.
It occupies a wide range of aquatic habitats throughout Australia, from slow, sandy creeks to large river channels and swampy lagoons, and, because of its wide ecological tolerance, this fish is able to thrive in an equally wide variety of water conditions in captivity. In the wild, M. trifasciata is most often seen in slightly alkaline waters which can vary from 75–90°F, but, as with most commercially bred aquarium fishes, it is not necessary to replicate these natural conditions all that closely.
Like most rainbowfishes, the diet is said to be an omnivorous mix of aquatic insects, worms and crustaceans, supplemented with the occasional bit of algae or plant matter. Captive individuals are equally catholic in their tastes and will feed voraciously on just about anything offered. As a shoaling species, it’s best to keep the Goyder River Rainbowfish in groups numbering six or more, and, to ensure this species reaches its full aesthetic potential, it is important to have a mix of both male and female specimens. The two sexes can be told apart by the more saturated coloration of the males, as well as their longer first dorsal fin and more extended dorsal and anal fin rays. Remember that specimens seen for sale in aquarium stores are usually immature specimens which have yet to fully color up.
For tankmates, almost anything will work with this amiable species, provided they aren’t big enough to swallow a rainbowfish whole. Its strong swimming abilities mean that even relatively aggressive groups like cichlids can usually be mixed without much concern, though, given how active rainbowfishes are, it is wise to avoid mixing them with overly timid fishes which might be frightened by their boisterous behaviors. With a maximum size of around 5 inches, this is one species that needs room to swim, so it is recommended that a rectangular aquarium of at least four feet is used, and, to provide a more accurate depiction of this fish’s natural habitat, be sure to heavily aquascape with live plants.