Hyphessobrycon hyanuary (Costello Tetra)

06 August 2026

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The Costello Tetra, scientifically known as Hyphessobrycon hyanuary, is a peaceful and active schooling fish native to the Amazon basin. Known for its subtle greenish-gold lateral stripe and distinctive black tail spot, this hardy tetra is a popular and undemanding choice for community aquariums.

Hyphessobrycon hyanuary (Costello Tetra)

Overview

The Costello Tetra, also known as the January Tetra (derived from its species name hyanuary), is a delightful and hardy freshwater fish belonging to the family Characidae. While not as vibrantly colored as the traditional Neon Tetra, it boasts a subtle, elegant beauty with its olive-green to silvery body and a striking black patch at the base of the tail, topped by a luminous golden-green stripe. It is highly regarded by aquarists for its peaceful nature and ease of care, making it an excellent addition to beginner and advanced community tanks alike.

Image of gruener neon hyphessobrycon hyanuary

Distribution and Habitat

This species is endemic to South America, specifically found in the upper Amazon River basin in Brazil. It was originally discovered in Lake Hyanuary, a floodplain lake near Manaus, which gave the fish its scientific name. In its natural habitat, the Costello Tetra inhabits slow-moving, heavily vegetated tributaries, flooded forests, and blackwater environments rich in tannins from decaying plant matter.

Description of Costello Tetra

Body shape:

The Costello Tetra features a classic tetra profile—laterally compressed and somewhat deep-bodied, allowing it to navigate easily through dense aquatic vegetation.

Color:

The base coloration is typically a silvery-olive or translucent grey. Its most defining feature is a prominent black spot on the caudal peduncle (the base of the tail), which is immediately bordered above by a reflective, iridescent golden-green line.

Barbels:

Like other characins, this species does not possess barbels.

Snout:

It has a relatively short snout with a terminal mouth, perfectly adapted for snatching small food particles from the water column.

Eyes:

The eyes are comparatively large with a bright, often slightly golden or silvery iris, aiding their vision in dimly lit blackwater environments.

Fins:

The fins are mostly translucent, though the dorsal and anal fins can sometimes show a faint whitish tint at their very tips.

The Tail:

The caudal fin is deeply forked and clear, with the distinct black blotch from the body often extending slightly into the base of the upper and lower lobes.

Temper

This is an exceptionally peaceful species. They do not nip fins or bother tank mates, making them ideal residents for a mixed community aquarium containing other small, docile fish.

Sociality

Costello Tetras are highly social, schooling fish. They must be kept in groups of at least 6 to 8 individuals to feel secure, display their best colors, and exhibit natural schooling behaviors. When kept alone or in too small of a group, they can become highly stressed and withdrawn.

Activity

They are very active swimmers that primarily occupy the middle and upper levels of the aquarium. They are constantly on the move, darting playfully among plants and open swimming spaces.

Keeping and Caring for Costello Tetra

Tank size:

A minimum tank size of 60 liters (15 gallons) is recommended for a small school. A longer tank is preferable as it provides more horizontal swimming space.

Water Parameters:

Temperature

They thrive in tropical temperatures ranging from 22 to 26°C (72-79°F).

pH

The ideal pH range is slightly acidic to neutral, between 6.0 and 7.5.

Hardness

They prefer soft to moderately hard water, ideally between 2 and 15 dGH.

Ammonia, Nitrite, Nitrate

Ammonia and Nitrite must always be at 0 ppm. Nitrates should be kept as low as possible, ideally below 20 ppm, through regular water changes.

Lighting

Subdued or moderate lighting is best. Floating plants can be used to diffuse bright aquarium lights, which will help the fish feel more secure and encourage them to show their best colors.

Water flow

A gentle to moderate water flow mimics their natural slow-moving habitat. Harsh currents should be avoided.

Decorations and Plants

A heavily planted tank with dark substrate is ideal. Incorporate driftwood, dried Indian almond leaves (to add beneficial tannins), and plenty of background and midground plants, while leaving a clear open area in the center for swimming.

Diet

Costello Tetras are omnivorous and not fussy eaters. In the aquarium, they will readily accept high-quality crushed flake foods and micro-pellets. To ensure optimal health and coloration, supplement their diet with live or frozen foods such as daphnia, brine shrimp, and bloodworms.

Some Feeding Tips

Feed them small amounts 1 to 2 times a day, only providing what they can consume within 2-3 minutes. Because they have small mouths, ensure all food particles are appropriately sized.

Breeding

Breeding the Costello Tetra is relatively straightforward as they are egg-scatterers that exhibit no parental care. To breed them, set up a separate dimly lit breeding tank with soft, slightly acidic water and fine-leaved plants like Java Moss or spawning mops. Condition the breeding pair or group with high-quality live foods. Spawning usually occurs in the early morning. Once eggs are scattered, the adult fish must be removed immediately to prevent them from eating the eggs. The fry will hatch in about 24 to 36 hours and will need to be fed infusoria or specialized liquid fry food until they are large enough to accept newly hatched brine shrimp.

Conclusion

The Costello Tetra (Hyphessobrycon hyanuary) is a fantastic, low-maintenance species that brings lively movement and subtle elegance to any freshwater setup. Their peaceful temperament, hardiness, and engaging schooling behavior make them an excellent choice for both novice fishkeepers setting up their first community tank and experienced aquarists looking for a classic Amazonian biotope resident.

Fish info

Care level: Easy
Temperament: Peaceful
Adult size: 4 cm
Life expectancy: 3-5 years
Fish type: Tetra
Temperature : 22-26°C
pH: 6.0-7.5
Color Form: Black, Gold, Green, Silver

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