Bloodfin Tetra

The bloodfin tetra stands out for the contrast between its slim, silvery body with a faint blue-green sheen and its blood-red tail, anal and pelvic fins. It is a fast species that is constantly on the move; it swims in a school in the upper layer of the aquarium.

Because it comes from a subtropical region, it adapts to a wide temperature range, is long-lived and is resistant to disease. It is an inexpensive, easy-to-find species suitable for beginners.

It lives in slow-flowing tributaries, ponds and planted shoreline areas of the Paraná River basin in Argentina and Paraguay. Seasonal temperature differences are marked in the region.

• Volume: at least 60 liters for a school of 8–12; a long tank (60 cm or more) suits its fast swimming.
• Water: 20–26°C; pH 6–8, soft to hard water.
• Lid: it is very prone to jumping; a tight-fitting lid is essential.
• Decor: plants along the edges and a large open area in the upper layer; it enjoys moderate flow.

Omnivorous. It eagerly takes flakes at the surface; vary it with small granules, frozen brine shrimp, daphnia and bloodworms. 1–2 meals a day is enough. Because it snatches food very quickly, make sure the slow and bottom-feeding species in the tank also get enough food.

Peaceful but very active. It constantly chases within the school; when the group is small it may nip the fins of slow, long-finned species. Because of its speed it outcompetes slow species at feeding time.

Good companions: danios, rasboras, other active tetras, corydoras, robust livebearers such as platies and mollies.

Avoid: long-finned, slow species such as bettas, fancy guppies and angelfish; large predators.

At least 8, ideally 12 or more individuals are recommended. A large school both moves more naturally and keeps the chasing within itself. The sex ratio does not matter. A large school making fast laps together in the upper layer is the most enjoyable sight this species offers in the aquarium.

It is an egg scatterer that breeds easily. A separate tank is prepared with shallow water and fine-leaved plants or a spawning grid; because the parents eat the eggs, they are removed after spawning. The eggs hatch in 1–2 days, and a few days later the fry start feeding on infusoria.

• Jumping: the most common cause of losses in tanks without a lid.
• Hardiness: it is resistant to disease; in good conditions it lives for many years.
• White spot (ich): may appear after sudden temperature changes.

Males have a more intense red in their fins and small hooks on the anal fin; because of these hooks they can get caught in nets. Females are paler and plumper.