Buenos Aires tetra

Quick facts

Adult size

7 cm

Lifespan

can live up to 6 years

Tank zone

mid

Temperament

semi-aggressive

Difficulty

beginner

Schooling

recommended 6+ (critical minimum 4, thrives at 10+)

Water parameters

Temperature

18–28°C

pH

6.0 to 8.0

Hardness

5 to 25 dGH

Tank requirements

Minimum volume

120 L

Minimum length

75 cm

Flow

moderate

Lighting

any

Substrate

any

Open swimming room

needed

Lid

required - jumper

Feeding

Diet: omnivore, feeds primarily at the mid.

Omnivore that eats everything with gusto. Flake, pellets, frozen bloodworm, frozen brine shrimp, blanched vegetables, algae, and live food. They also eat aquatic plants, which is a feature or a problem depending on your tank. Include vegetable matter in the diet to reduce plant destruction (give them something to eat that isn't your aquascape). Feed twice daily. Not picky, not slow, not shy.

Vegetable matter required (algae wafers, blanched zucchini, spinach).

Compatibility

• One of the tougher, more assertive tetras. Larger (7 cm) and more boisterous than most common tetras. Occasional fin-nipper, especially in small groups.
• Groups of 8+ reduce nipping behavior. In large schools they form a hierarchy and leave tankmates alone. Small groups (under 6) are noticeably more aggressive toward other species.
• Not safe for planted tanks. Buenos Aires tetras eat soft-leaved aquatic plants with enthusiasm. Java fern and Anubias (tough leaves) are usually left alone; everything else is food.
• Good companions: other barbs, larger tetras, rainbowfish, and catfish. Avoid long-finned species and small delicate fish.

Habitat

Native to the Parana and Uruguay River basins in Argentina, Brazil, Paraguay, and Uruguay. Found in subtropical to warm-temperate rivers and streams with moderate flow. The species (Hyphessobrycon anisitsi) tolerates a wide temperature range (16–28°C), making it suitable for both tropical and unheated indoor tanks. The body is silver with a subtle blue sheen, a red caudal fin, and faint red in the dorsal and anal fins. A thin dark lateral line runs from behind the gill cover to the base of the tail. Males are slimmer with more vivid fin color; females are deeper-bodied. Adult size is 6–7 cm, making them one of the larger commonly available Hyphessobrycon species. The species has been in the hobby since the early 1920s. All stock is commercially bred. They're often overlooked because they lack the flash of neon or cardinal tetras, but a large school in a well-lit tank is attractive.

Breeding

Easy egg scatterer. Tolerates a wide range of water conditions for breeding, including moderately hard water that would prevent most Amazon tetras from spawning. Condition a pair with frozen food. Breeding tank with fine-leaved plants or spawning mops. The pair scatters 500-1000 eggs (large clutch for a tetra) among the plants at dawn. Eggs are semi-adhesive. Adults eat eggs; remove promptly. Eggs hatch in 24-30 hours. Fry take baby brine shrimp within 3-4 days. Growth is fast. One of the simpler tetras to breed at home.

Common problems

Plant destruction is the main issue. Buenos Aires tetras are among the worst plant eaters in the tetra family. A school of 10 will strip a moderately planted tank within a week. Keeping them means accepting a non-planted tank or using only tough-leaved species. Health problems are rare; they're extremely hardy. Nipping in small groups is solved by increasing group size. Cold tolerance means they handle temperature fluctuations that would stress tropical tetras.

Bioload

Bioload coefficient: 2.5 (medium tetra; moderate waste for a schooler).

Bioload coefficients are calibrated against the neon tetra as the anchor (1.0). See the methodology page for the formula and how each value was derived.

Further reading

• How to cycle a fish tank
• Stocking ideas by tank size