Duboulay's Rainbowfish

Adult fish reach a maximum length of about 12 cm, though in the aquarium they are usually somewhat smaller, around 10 cm. The body is laterally compressed and slender. The anal fin extends from the middle of the belly to the tail, and the dorsal fin is divided into two parts, the first noticeably shorter than the second. Coloration varies depending on the fish's origin, but generally the body is silvery with hints of blue, green and yellow. A distinctive crimson spot marks the gill cover, and the fins are red or blue with a noticeable black edge. Males are more intensely coloured than females and have pointed dorsal and anal fin tips, whereas females have more rounded fins.

Duboulay's rainbowfish is native to the east coast of Australia, where it inhabits subtropical regions. The fish occurs in rivers, streams, swamps and lakes rich in aquatic vegetation. Its natural habitat experiences constant seasonal changes in temperature, water level and water chemistry. Outside Australia, the species is known chiefly as an aquarium fish, kept since the early twentieth century, though no established wild populations have been recorded on other continents.

These fish prefer to live in groups in which females predominate. Males are more solitary or keep somewhat apart. They are peaceful toward other species and do well with fish of similar size and temperament.

A group of 6–8 fish needs an aquarium of 150–200 litres or more. In their natural habitat, Duboulay's rainbowfish spend much time swimming around dense plant growth, driftwood and other submerged objects that serve as refuge. When setting up the tank, combine open swimming areas with plenty of shelter, such as plants. These fish have evolved to tolerate a wide range of conditions, enduring varied temperatures, pH and water hardness. Because of this adaptability, they are easy to keep. Maintain clean, warm water and carry out regular tank maintenance, including equipment care.

In the wild, their diet consists of plant material and small invertebrates. In the aquarium, Duboulay's rainbowfish eat both dry and freeze-dried foods in the form of flakes or granules.

In their natural habitat, spawning occurs from September to December, coinciding with the start of the summer rains (warm months in the Southern Hemisphere). In the aquarium, spawning is not seasonal. Eggs are laid in dim light among plants, attached to leaf surfaces. Females lay only a few eggs daily, so spawning may extend over several weeks. The incubation period is 5–9 days at water temperatures of 24–29 °C. The fry immediately form a group and stay near the surface. After 12 hours they begin to feed. For the first days their diet must consist entirely of microfood such as infusoria. As they grow they move on to larger food. Mixed-age fry can make feeding difficult. Although adults do not tend to prey on their young, moving the fry to a separate tank is recommended for easier care.

Illness is rare in these fish when conditions are favourable. If signs of disease appear, such as lethargy, body deformity or spots, check water quality first. Often restoring all parameters to normal allows the fish to recover on its own. If not, medication may be needed.

When selecting fish, choose active individuals with clean scales, free from visible damage, spots or signs of starvation. Healthy fish show vibrant colour and curiosity about their surroundings. Avoid fish that stay isolated, remain constantly at the surface or bottom, or have sunken bellies, as these may indicate parasites or chronic stress. Fish in the shop should display schooling behaviour and respond properly to feeding.