Moenkhausia rubra Care Guide - Tank Setup, Diet & Breeding

Moenkhausia rubra is a small, streamlined characin with a warm reddish to coppery body and translucent fins. In good condition, the colour becomes noticeably richer, particularly across the flanks and toward the rear of the body. Its reflective scales catch the light as the fish turns, giving a shoal a lively, shimmering appearance.

This species is an active but generally peaceful swimmer. It spends much of its time in the middle levels of the aquarium, where it moves confidently with its companions and displays mild, non-damaging social sparring. Groups are most impressive when they have enough members to form a stable shoal.

In nature, Moenkhausia rubra is associated with tropical streams and tributaries containing submerged branches, leaf litter and aquatic or overhanging vegetation. The surrounding cover breaks up the light and provides shelter, while the flowing water carries small invertebrates and other food items through the habitat.

Like many small characins, it is best appreciated as a group fish rather than as a solitary specimen. Its attractive colour, modest adult size and active nature make it an appealing choice for a peaceful South American community aquarium.

Moenkhausia rubra is a South American freshwater tetra native to Brazil. It occurs in clear to lightly stained tributaries of the Amazon basin, where it inhabits warm, gently flowing waters surrounded by dense vegetation.

A group should be given at least 80 litres, with a tank around 90 cm long preferred so there is sufficient uninterrupted swimming space. Use a dark, fine-grained substrate with driftwood, smooth branches, leaf litter and hardy plants arranged around open central water. Moderate filtration, gentle circulation and subdued or diffused lighting suit its stream habitat, while floating plants can provide additional shade. A secure lid is useful because active characins may jump.

Adults reach about 4.5 cm (1.8 in) in standard length. Females are usually slightly larger and deeper-bodied than males.

This omnivorous tetra accepts quality small pellets, flakes and microgranules, supplemented with frozen or live foods such as baby brine shrimp, daphnia, mosquito larvae and finely chopped bloodworm. Regular vegetable-based ingredients can also form part of a varied diet. Feed small portions that the group can consume quickly, with food sized for their small mouths.

Moenkhausia rubra is a peaceful community fish and can be kept with similarly sized tetras, rasboras, small peaceful barbs, pencilfish, Corydoras and other non-aggressive South American species. It may also live alongside small peaceful catfish and dwarf cichlids that do not regard it as prey. Avoid large predatory fish, aggressive cichlids and persistent fin-nippers, as well as very slow or exceptionally timid species that may be stressed by its activity.

Moenkhausia rubra is an egg-scattering characin that can be bred in a separate, dimly lit breeding aquarium. Use soft, slightly acidic water and provide fine-leaved plants or spawning mops for the eggs to fall into. Condition the adults with live or frozen foods, then introduce a pair or small group. Remove the adults after spawning, as they may eat the eggs. The eggs usually hatch within a day or two, and the tiny fry can be raised on infusoria before moving on to newly hatched brine shrimp.

Females are generally fuller through the abdomen, especially when carrying eggs, while males tend to be slimmer and may show more intense colour. The differences are subtle outside breeding condition.