Hyphessobrycon myrmex (Ant Tetra)

Overview

The Ant Tetra (Hyphessobrycon myrmex) is a fascinating, relatively new addition to the aquarium hobby. First described in the late 2010s, this species has quickly gained a dedicated following due to its unique sexual dimorphism and peaceful nature. The "nz" in the trade often refers to "Nachzucht," meaning these are captive-bred specimens, which adapt more easily to aquarium conditions than wild-caught counterparts.

Distribution and Habitat

Native to South America, the Ant Tetra originates from the Rio Juruena basin in the Mato Grosso region of Brazil. They inhabit clear, slow-moving streams and tributaries that are often shaded by dense overhanging vegetation. The water in these natural habitats is typically soft and slightly acidic, enriched by fallen leaves and submerged wood.

Description of Ant Tetra

This species is celebrated for its distinct visual differences between males and females, making it an intriguing subject for planted aquariums.

Body shape:

They possess a classic tetra profile: laterally compressed, somewhat deep-bodied, and streamlined for efficient swimming in the middle water column.

Color:

Sexual dimorphism is extreme. Adult males display a stunning, deep reddish-orange to golden-yellow coloration, while females and juveniles are much more subdued, exhibiting a pale silvery-grey to light yellow hue. Both sexes share a distinct dark lateral stripe extending towards the tail.

Barbels:

Like all species in the Characidae family, the Ant Tetra does not possess any barbels.

Snout:

They feature a short, blunt snout with a terminal mouth adapted for picking small insects and zooplankton from the water column.

Eyes:

The eyes are relatively large with a dark pupil and a reflective, sometimes orange-tinted iris, aiding in low-light vision.

Fins:

They have translucent to slightly tinted fins, including a prominent dorsal fin, anal fin, and a small adipose fin characteristic of characins.

The Tail:

The caudal fin is deeply forked, allowing for quick, agile movements when evading predators or chasing food.

Temper

The Ant Tetra is an exceptionally peaceful species. They do not bother other fish and are generally timid, relying on the safety of their school to feel secure.

Sociality

They are highly gregarious schooling fish. It is highly recommended to keep them in groups of at least 8 to 10 individuals. A larger group not only reduces stress but also encourages males to display their best colors as they harmlessly spar for female attention.

Activity

These tetras are active swimmers, primarily occupying the middle and upper levels of the aquarium. They are diurnal, spending their days exploring the plants and waiting for food.

Keeping and Caring for Ant Tetra

While captive-bred specimens are hardy, they still thrive best when their environment mimics their natural South American habitat.

Tank size:

A minimum tank size of 60 liters (15 gallons) is recommended for a small school, though larger tanks are preferable to provide ample swimming space.

Water Parameters:

Stability is key. They prefer clean, well-oxygenated water with parameters that lean towards the softer, acidic side.

Temperature

Maintain the water temperature between 24°C and 28°C (75°F - 82°F).

pH

A slightly acidic to neutral pH ranging from 6.0 to 7.0 is ideal.

Hardness

Soft water is preferred, generally between 2 and 10 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 to moderate lighting is best. Floating plants can be used to diffuse bright lights, which helps the fish feel more secure and enhances their coloration.

Water flow

They appreciate a gentle to moderate water flow that simulates a slow-moving stream without overpowering them.

Decorations and Plants

A heavily planted tank with dark substrate, driftwood, and dried leaf litter (such as Indian Almond leaves) provides the perfect environment. The tannins from the wood and leaves will also naturally lower the pH and mimic blackwater conditions.

Diet

In the wild, they are micro-predators feeding on tiny invertebrates. In the aquarium, they are unfussy omnivores that will readily accept high-quality dry foods, as well as live and frozen foods like Daphnia, baby brine shrimp, and bloodworms.

Some Feeding Tips

Feed small amounts 1-2 times a day. Because they have small mouths, ensure that pellets or granules are appropriately sized. Variety is crucial for maintaining the vibrant colors of the males.

Breeding

Breeding the Ant Tetra is similar to other Hyphessobrycon species. They are egg scatterers that exhibit no parental care. To breed them, set up a separate dim breeding tank with very soft, acidic water and plenty of fine-leaved plants or a spawning mop. The distinct sexual dimorphism makes picking a healthy pair or breeding group very easy. Once eggs are laid, adult fish should be removed to prevent them from eating the eggs.

Conclusion

The Ant Tetra is a truly spectacular, peaceful schooling fish that rewards the dedicated aquarist with fascinating behavior and stunning colors. Whether you are building a South American biotope or a lush aquascape, a healthy school of Hyphessobrycon myrmex will undoubtedly be a captivating centerpiece.