Blyth River Banded Rainbowfish

Melanotaenia trifasciata

General information: Banded Rainbowfish vary in appearance depending on which river system they are found. The form from the Blyth River resembles the very well known Goyder River form. This species can grow to 12 cm but is usually 10 cm full grown. The sexes in the banded rainbowfish are a little more difficult to differentiate but generally males are more colourful with slightly deeper bodies, the males have slightly longer fins but this is not as pronounced as in other rainbowfishes. The habitat where brood stock was collected is a small spring fed stream, upper Blyth River, with a fast side stream off the main channel. This rainbowfish species was not found swimming with the other rainbowfish species in the same water, it was in the faster water in a well shaded area. Water quality measurements were taken when the broodstock was collected. The measurements were made in the dry season. Temperature 27, pH 7.6, Alkalinity or carbonate hardness 100ppm and hardness 90ppm. Wild rainbowfish diets are reported to include algae, aquatic insects and small crustaceans. The male finds a location and displays to females that are near. Females can lay approx 40 to 100 eggs a day if conditions are good. The Blyth River is between Maningrida and Raminginning and runs north into the Arafura Sea. The broodstock were collected within an agreement with the traditional owner of the area. A percentage of sales goes back to Otto and his family to assist with their land management. This is a form of sustainable use of wildlife.

Cultivation notes : It is recommended that a minimum size for an aquarium to keep a small group of these fish is 90 cm. They are a schooling fish and are best kept in a group of five or more, with a ratio of two to one males to females will get the best colour display each morning. The banded rainbowfish appears to need higher dissolved oxygen levels than other rainbowfishes and is the first affected if the carbon dioxide plant fetiliser is adding too much co2 or some other factor lowers dissolved oxygen levels. They like clean well oxygenated water and will benefit from plenty of water movement. Water quality parameters are not too important as the species has broad tolerances except low dissolved oxygen. In captivity rainbowfishes will accept most prepared foods supplied. It is best if they can be offered at least one third to a half vegetable matter. About 5 adults with three females are a good number to use for breeding. Spawning mops can be used to collect eggs from a group of fish in an aquarium. Eggs hatch in a few days to a week and can be raised easily using commercially available fry feeds and plankton cultures. They are a peaceful fish that will fit in well with most other fishes of the same size.

Distribution : Recorded from several places in North Queensland and across the top of the Northern Territory.

Selling details : Sold individually at 3.0 centimetres or larger total length.

Reference: Allen G.R., Midgley S.H. and Allen M. (2002) "Freshwater Fishes of Australia"] ANGFA database -