Hyphessobrycon sweglesi, known in the trade as the Red Phantom Tetra, is a small characin originating from slow-flowing, vegetated waters in northern South America. It is appreciated for its translucent red body, prominent dark shoulder spot and delicate, extended fins that create a graceful, “phantom-like” appearance in the aquarium.

This species remains small (around 3–4 cm adult length), making it an excellent choice for medium-sized community aquariums where a peaceful, schooling centrepiece is desired. When kept in suitable conditions, the fish exhibit calm, coordinated swimming and subtle hierarchy behaviour that adds constant yet gentle movement to the tank.

Care level and suitability for beginners

Hyphessobrycon sweglesi can be recommended for beginners who are willing to follow basic good practice in aquarium maintenance. The species is not aggressive and adapts well to community setups, but it does require:

• Stable, clean water with low nitrate levels.

• Soft, slightly acidic water values that do not fluctuate suddenly.

• Regular, moderate water changes and careful acclimation.

Beginners who already have a cycled aquarium and who test and adjust water parameters will find this fish rewarding and relatively forgiving compared with more delicate tetras.

Aquarium setup and environment

To replicate the natural environment of Red Phantom Tetras and support their health and behaviour, the aquarium should include:

• A minimum tank length of 60–80 cm, providing enough horizontal space for a group to school.

• Dense live planting (e.g. stem plants, floating plants, fine-leaved species) to provide cover and visual barriers.

• Dark sand or fine gravel substrate, with driftwood, roots and leaf litter to create a natural, shaded look.

• Gentle filtration that provides clean water and soft current but avoids strong turbulence.

• Subdued lighting, often achieved with floating plants, to encourage more intense colouration and reduce stress.

These fish occupy the middle and upper layers of the tank, so open swimming space in front of a planted background will allow them to display naturally.

Water parameters and maintenance

Red Phantom Tetras are most comfortable in soft, slightly acidic water similar to their native habitats. For long-term success:

• Temperature: Maintain in the range of 22–26 °C, avoiding rapid changes.

• pH: Aim for 5.5–7.0, with gradual adjustments if required.

• Hardness: Prefer soft to moderately soft water; avoid very hard water when possible.

• Routine: Perform regular partial water changes (e.g. 20–30% weekly) to control waste and maintain stable parameters.

Using a reliable heater, thermometer and liquid test kits is recommended so that beginners can monitor conditions and adjust slowly if needed.

Social behaviour and compatibility

Hyphessobrycon sweglesi is a peaceful schooling species that must be kept in groups of at least 8 individuals. In smaller numbers the fish can become shy and show less colour; in larger shoals their confidence increases and natural social behaviour becomes visible.

Suitable tank mates include:

• Other small, peaceful tetras and rasboras.

• Small Corydoras and similar bottom-dwelling catfish.

• Dwarf or very peaceful small cichlids that do not view them as prey.

• Non-aggressive invertebrates where compatible with water parameters.

Avoid keeping them with large, boisterous or predatory fish that may intimidate or attempt to eat them. A calm community setting ensures the fish remain active and display their full colour range.

Feeding and nutrition

In nature, Red Phantom Tetras consume small invertebrates, micro-crustaceans and plant material, and they adapt well to a varied omnivorous diet in the aquarium. For best health and colour:

• Offer high-quality micro flakes or small pellets as the staple diet.

• Supplement regularly with frozen or live foods such as daphnia, cyclops, baby brine shrimp and finely chopped bloodworms.

• Feed small portions 1–2 times per day, ensuring all food is consumed within a few minutes to maintain water quality.

A varied diet supports strong immune function, good growth and enhanced red pigmentation.

Breeding notes (for interested hobbyists)

Hyphessobrycon sweglesi is an egg-scattering species and will sometimes spawn in a well-maintained community aquarium, although eggs and fry are usually eaten by adults or tank mates. Dedicated breeding attempts require:

• A separate breeding tank with very soft, slightly acidic water and fine-leaved plants or spawning mops.

• A conditioned pair or small group fed heavily on frozen and live foods.

• Removal of adults after spawning to protect eggs, followed by careful rearing of the fry with suitable fry foods.

While breeding is not essential for keeping this species, understanding its reproductive behaviour can be an interesting project for more experienced beginners.