Red Rainbowfish Care Guide - Aquarium Setup, Diet & Breeding

The Red Rainbowfish is a large, high-bodied species with a deep, laterally compressed profile and an attractive iridescent sheen. Mature males develop rich red to orange-red colouring across the body, often contrasted by darker scale margins and shimmering blue-green reflections. Females are usually more silvery, olive or yellowish, with less intense colouration.

These fish are active, confident swimmers that spend much of their time in the open water. Males may display to one another by intensifying their colours and presenting their bodies side on, particularly when competing for the attention of females. Their energetic behaviour makes them an eye-catching feature in a spacious aquarium.

In the wild, Red Rainbowfish live in warm, clear to lightly stained freshwater habitats around Lake Sentani. The lake contains rocky margins, submerged vegetation and open areas where these schooling fish can move and forage. Seasonal changes in rainfall influence water levels and the character of the surrounding wetlands.

Glossolepis incisus was one of the earliest rainbowfish species to become well known in the aquarium hobby. Its striking adult male colouration develops gradually, so younger specimens can look comparatively plain before reaching maturity. With age, males become especially impressive and are often regarded as one of the showiest larger rainbowfish.

Red Rainbowfish are native to Lake Sentani and nearby waterways in Papua, Indonesia, on the island of New Guinea. They inhabit freshwater lakes, streams and connected wetlands in the lake’s surrounding region.

A group of Red Rainbowfish should have at least a 200-litre aquarium, with a tank measuring around 120 cm in length preferred because these active swimmers need ample uninterrupted space. Use a secure lid, efficient filtration and good water movement while leaving open swimming areas through the centre of the aquarium. A dark, fine-grained or smooth gravel substrate, hardy plants around the sides and back, driftwood and rounded stones create a natural-looking layout without crowding the fish. Allow plenty of surface area and avoid sharp decor that could damage their fast-moving bodies.

Males can reach about 15 cm (6 in) in length, while females usually grow to around 12 cm (4.7 in).

Red Rainbowfish are omnivores and thrive on a varied diet. Offer a quality flake or small-to-medium pellet as a staple, supplemented with frozen or live foods such as brine shrimp, bloodworm, daphnia and mosquito larvae. Small portions of soft vegetable matter, spirulina-based foods or blanched greens can also be included. Feeding modest portions several times a day is useful for growing fish and encourages strong colour and condition in adults.

Red Rainbowfish are generally peaceful but large, fast-moving and highly active, so they are best kept with similarly sized, robust community fish. Suitable companions can include larger peaceful rainbowfish, Congo tetras, peaceful barbs, larger rasboras, peaceful gouramis and non-aggressive catfish such as bristlenose plecos or larger Corydoras. Avoid slow, delicate or very small fish that may be intimidated or outcompeted, as well as fin-nippers and aggressive cichlids. Keeping them in a proper group helps spread attention and reduces the chance of persistent male-to-male harassment.

Red Rainbowfish are egg scatterers that can breed readily when mature, well-conditioned fish are given abundant live or frozen foods. Provide fine-leaved plants or spawning mops, where females deposit adhesive eggs among the strands and males fertilise them. Move the spawning material to a separate, gently aerated tank to protect the eggs from being eaten. At around 7 to 10 days, depending on temperature, the fry hatch and can be raised on infusoria or a suitably fine first food before progressing to baby brine shrimp.

Mature males are larger and develop vivid red or orange-red bodies with stronger iridescent markings. Females are generally smaller and remain silvery, olive or yellowish, with noticeably less intense colouration.