Redline Tetra Care Guide - Aquarium Setup, Diet & Breeding

The Redline Tetra is a small, elegant characin with a translucent silver body and a vivid red stripe running from the eye along the upper side of the body toward the tail. A warm golden or copper glow often appears beneath the red line, especially when the fish are settled and displaying their colour well. The fins are mostly transparent, with subtle pale markings.

Peaceful, active and sociable, Redline Tetras spend much of their time moving through the middle levels of the aquarium. In a group they form a loosely coordinated shoal, becoming more confident and expressive as their numbers increase. They are lively without usually being boisterous enough to trouble calm community fish.

In the wild, they are associated with forest streams where overhanging plants, roots and leaf litter break up the light and provide shelter. Their streamlined shape and reflective colouring suit life in these dimly lit waters, where flashes of red can appear and disappear as the shoal moves among the vegetation.

Hemigrammus erythrozonus was described from Guyana and has become a popular aquarium tetra because of its manageable size, peaceful temperament and distinctive neon-like red lateral stripe. Healthy specimens often show stronger colour as they mature and feel secure within a suitable group.

Redline Tetras are native to the Essequibo River basin in Guyana, South America. They inhabit slow-moving, shaded rainforest streams and tributaries, often in soft, tannin-stained blackwater surrounded by dense vegetation.

A group of Redline Tetras should be kept in an aquarium of at least 60 litres, with a footprint around 60 × 30 cm or larger. Use gentle filtration and provide open swimming space alongside dense plants, floating vegetation, driftwood and shaded areas that reflect their natural forest-stream habitat. A dark, fine-grained substrate helps them feel secure and enhances their colours, while leaf litter or other natural refuges can add useful cover. Keep the aquarium mature, stable and well maintained.

Up to 4 cm (1.6 in) in length. Females are generally slightly larger and deeper-bodied than males.

Redline Tetras are omnivores and do best on a varied diet of quality small tropical flakes or micro-pellets supplemented with frozen or live foods such as daphnia, baby brine shrimp, cyclops and mosquito larvae. Their small mouths require appropriately sized portions. Feeding small amounts once or twice daily helps them obtain food without leaving excessive waste in the aquarium.

Redline Tetras are well suited to peaceful community aquariums. Good companions include small rasboras, other gentle tetras, pencilfish, small Corydoras, Otocinclus and peaceful dwarf cichlids such as Apistogramma. Avoid large predatory fish, fin-nippers and very boisterous species, which may harass them or view them as prey. They should also not be housed with aggressive or highly territorial tankmates.

Redline Tetras are egg-scattering fish that breed most readily in a separate, dimly lit breeding aquarium with soft, slightly acidic water and fine-leaved plants or a spawning mop. Condition the adults with live or frozen foods, then introduce a pair or small group. After spawning, remove the adults because they may eat the eggs. The eggs usually hatch within about 24 hours, and the tiny fry can initially be fed infusoria or another suitably fine first food before progressing to baby brine shrimp.

Females are usually fuller through the abdomen, particularly when carrying eggs, while males tend to be slimmer and more streamlined. The difference can be subtle, and colouration is not a consistently reliable way to sex them.