Green Fire Tetra Care Guide - Aquarium Setup, Diet & Breeding

The Green Fire Tetra is a small, lively characin with a slender, silvery body and translucent fins. Depending on its mood and lighting, the body can show a subtle green-gold sheen, while the fins may display warm yellow, orange, or reddish tones that give this fish its fiery common name.

A peaceful but active species, it spends much of its time in the middle and upper levels of the aquarium. Green Fire Tetras are most engaging when kept in a proper shoal, where they swim confidently, investigate their surroundings, and display gentle social interactions without forming a rigid hierarchy.

In the wild, Aphyocharax rathbuni inhabits vegetated streams, quiet river margins, and smaller waterways associated with the Paraguay and Paraná basins. These habitats can include leaf litter, submerged roots, and areas of broken shade, creating a varied environment for a small schooling fish.

Its understated appearance is enhanced by movement, with a coordinated group flashing through the water as the fish turn together. Green Fire Tetras are a good choice for aquarists who enjoy active South American community fish but want a species that remains considerably smaller than many of the larger characins.

Green Fire Tetras, also known as Rathbun’s Tetras, are native to the southern part of South America. They occur in the Paraguay and Paraná river systems, particularly across Paraguay, southern Brazil, and northern Argentina.

A group should be given at least a 60-litre aquarium, with a footprint of approximately 60 × 30 cm or larger to provide uninterrupted swimming space. Use a fine gravel or sand substrate, areas of dense planting, and some driftwood or branching decor to create cover without filling the whole tank. Floating plants can soften the lighting, while open water at the front and centre allows the shoal to move naturally. A secure lid is advisable because active fish may jump.

Green Fire Tetras reach a maximum adult length of about 4 cm (1.6 in). Females are usually slightly deeper-bodied and may be a little larger than males, which are generally slimmer.

Green Fire Tetras are omnivores and do best on a varied diet of quality small flakes or micro-pellets supplemented with frozen or live foods. Daphnia, baby brine shrimp, cyclops, and suitably sized bloodworms provide useful variety and encourage natural feeding behaviour. Feed small portions that the group can consume promptly, rather than offering one large meal.

Green Fire Tetras can live with other peaceful fish of a similar size, including small Corydoras, peaceful rasboras, other gentle tetras, pencilfish, otocinclus, and non-aggressive dwarf cichlids. They are generally community-friendly, although larger or predatory fish may view them as prey. Avoid housing them with aggressive species, boisterous fin-nippers, or very slow fish that may be unsettled by their constant activity.

Green Fire Tetras are egg-scattering spawners that can be bred in a separate, dimly lit aquarium containing fine-leaved plants or a spawning mop. Condition a group with plenty of small live or frozen foods, then introduce the fish when females are full of eggs. Remove the adults after spawning, as they may eat the eggs. The eggs generally hatch within a day or two, and the tiny fry can initially be fed infusoria or another suitably fine first food before moving on to newly hatched brine shrimp.

Mature females are typically fuller through the abdomen, particularly when carrying eggs, while males tend to have a slimmer profile. Males may also show more intense colour in the fins, although sex differences can be subtle outside of breeding condition.