African Blue Diamond Tetra Care Guide - Aquarium Setup, Diet & Breeding

The African Blue Diamond Tetra is a striking African characin with a silvery body overlaid by an intense blue-green metallic sheen. When mature, its colour can become particularly vivid across the flanks, while the fins may show warm yellow, orange or reddish tones and delicate dark markings. Males often develop the most impressive finnage and coloration.

This is an active, elegant schooling fish that spends much of its time in the middle and upper levels of the aquarium. In a settled group, the fish display constantly shifting social interactions, with males posturing and sparring harmlessly as they establish a visual hierarchy.

In the wild, the species is associated with flowing forest waterways, tributaries and quieter margins where submerged branches, leaf litter and aquatic vegetation create a broken pattern of shade and cover. The dark, reflective water helps emphasise its blue metallic body.

Alestopetersius caudalis belongs to the African characin family Alestidae, a group that includes several well-known Congo Basin aquarium fishes. Although less commonly seen than the Congo Tetra, the African Blue Diamond Tetra is valued for its lively behaviour, attractive colour and distinctly African character.

African Blue Diamond Tetras come from the Congo River basin in Central Africa, particularly the Democratic Republic of the Congo and neighbouring parts of the Republic of the Congo. They inhabit forested rivers and tributaries with flowing, often tannin-stained water.

A group should be kept in an aquarium of at least 120 litres, with a footprint of around 90 x 40 cm or larger to provide uninterrupted swimming space. Use a dark, fine substrate with driftwood, smooth roots, leaf litter and areas of dense planting around the edges, while leaving an open central area for schooling. Moderate water movement, subdued or filtered lighting and floating plants help recreate the shaded character of their forest-stream habitat. A secure lid is advisable because active characins can jump.

Up to about 6.5 cm (2.6 inches) in total length. Males are usually slightly larger and more heavily finned than females.

They are adaptable omnivores that feed on small insects, crustaceans and other invertebrates in nature, along with occasional plant material. Offer a varied diet of quality small pellets or flakes supplemented with frozen or live foods such as bloodworm, daphnia, brine shrimp and mosquito larvae. Small, regular meals help maintain their colour, energy and condition.

African Blue Diamond Tetras are generally peaceful when kept in a proper group and make good companions for similarly sized, robust community fish. Suitable tankmates include Congo Tetras, other peaceful African characins, larger rasboras, peaceful barbs, rainbowfish, Corydoras and non-aggressive dwarf cichlids. Avoid highly aggressive species, fin-nippers and very timid fish that may be overwhelmed by their activity. They should not be housed with large predatory fish or boisterous tankmates that could injure or continually intimidate them.

African Blue Diamond Tetras are egg-scattering free spawners. Condition a group with plentiful live or frozen foods, then place the fish in a separate, mature breeding aquarium with soft, slightly acidic water, subdued lighting and fine-leaved plants or spawning mops. Spawning usually takes place among the vegetation, with eggs scattered widely. Remove the adults after spawning because they may eat the eggs. The eggs generally hatch within a few days, and the tiny fry can be raised on infusoria or other suitably fine first foods before moving on to baby brine shrimp.

Males are typically more slender, brighter blue and more elaborately finned, with extended rays or trailing edges on some fins as they mature. Females are usually deeper-bodied, especially when carrying eggs, and tend to have shorter, less ornate fins.