Buenos Aires Tetra

The Buenos Aires tetra is recognized by its silver body with bluish-green reflections, its reddish fins and the black, arrowhead-shaped mark extending from the tail base to the middle of the tail. It is a sturdily built tetra that grows up to 7 cm. An albino form is also widely sold.

It is very hardy and has a big appetite, and it adapts to a wide temperature range. However, it has two important traits: it eats soft-leaved plants and in a small group it nips fins. For this reason it is not suitable for every community aquarium.

It lives in lakes, swamps and slow-flowing shoreline areas of the Paraná and La Plata river systems in Argentina, Paraguay and southern Brazil. Because it comes from a subtropical region, it is used to seasonal temperature changes.

• Volume: at least 100 liters for a group of 6–8; a length of 80 cm or more.
• Water: 20–26°C; it can also live in unheated rooms. pH 6–8, soft to hard water.
• Plants: soft-leaved plants are eaten quickly. Hard-leaved plants such as Anubias, Java fern and Bolbitis, or artificial plants, should be preferred.
• Lid: it is an active species; a covered aquarium is recommended.

Omnivorous and needs plant-based food. Flakes and granules containing spirulina, blanched spinach or lettuce leaves and zucchini slices reduce its interest in plants. Provide protein with frozen bloodworms, brine shrimp and mysis shrimp.

Active and energetic. It constantly chases within its own group; in a small group this energy turns toward other fish and becomes fin nipping. It hunts small shrimp and shrimplets.

Good companions: fast, robust species of similar size: large barbs, danios, Congo tetras, medium-sized cichlids such as convicts and acaras, plecos, large corydoras.

Avoid: long-finned species (betta, angelfish, fancy guppies), very small and slow fish, dwarf shrimp, planted tanks with soft plants.

At least 6, ideally 8 or more individuals are recommended. In a large group the chasing is spread out within the school; when kept in small numbers, aggression increases. The sex ratio does not matter.

It breeds easily. In a separate tank it lays a large number of eggs on fine-leaved plants or a spawning mop. The parents must be removed because they eat the eggs. The eggs hatch in 1–2 days; the fry become free-swimming a few days later and are fed first infusoria, then newly hatched brine shrimp.

• Hardiness: it is very resistant to disease.
• White spot (ich): may appear after sudden, large temperature changes.
• Nutritional deficiency: fish that are not given plant-based food eat plants faster; a balanced menu also matters for health.

Males are more slender and have more intense red on their fins. Females are larger with a plumper belly.