Red Tail Hemiodus Tetra Care Guide - Aquarium Setup, Diet & Breeding

The Red Tail Hemiodus Tetra is a streamlined, silvery characin with a distinctive dark stripe running along the body and a vivid red to orange-red tail. Its reflective scales catch the light as the fish turns, while the elongated shape gives it a purposeful, fast-swimming appearance. The species is sometimes sold simply as the Red Tail Hemiodus or Gracilis Hemiodus.

This is an active, peaceful schooling fish that spends much of its time in the middle and upper levels of the aquarium. In a confident group, the fish move together in coordinated bursts, regularly exploring the open water and responding quickly to movement around the tank.

In the wild, Hemiodus gracilis is associated with warm South American rivers and tributaries, where current, submerged wood and vegetation provide structure without removing the open swimming space these fish prefer. Seasonal changes in water flow and food availability influence the rhythm of life in these habitats.

Although it has the appearance of a typical large tetra, the Red Tail Hemiodus is more substantial and energetic than many small community tetras. Its combination of a silver body, bold lateral marking and red tail makes a group especially striking in a spacious planted aquarium.

Red Tail Hemiodus Tetras are native to tropical South America, with Hemiodus gracilis occurring in the Amazon basin and neighbouring northern South American waterways. They inhabit warm, flowing freshwater environments associated with forested rivers and tributaries.

A group should be provided with an aquarium of at least 200 litres, ideally measuring around 120 cm long by 45 cm wide or more, because these powerful swimmers need uninterrupted horizontal space. Use efficient filtration with good oxygenation and a gentle to moderate current, while leaving calmer areas for resting. A dark sand or fine-gravel substrate, driftwood, smooth stones and groups of hardy plants can recreate a river-edge setting, but the centre and front of the aquarium should remain open for swimming. A secure cover is advisable because active Hemiodus can jump.

Up to about 10 cm (4 in) in total length. Females may become slightly deeper-bodied and heavier than males, although the difference is usually modest.

Red Tail Hemiodus Tetras are omnivores with a strong tendency to graze on plant material and algae while also taking small aquatic invertebrates. Offer a varied diet of quality flakes, small sinking or floating pellets, spirulina-based foods, frozen or live daphnia, brine shrimp and bloodworm. Regular portions of blanched spinach, courgette or other soft vegetable matter can supplement their diet, while small, frequent meals help support their active lifestyle.

Red Tail Hemiodus Tetras can be kept with other peaceful, similarly sized community fish, including larger tetras, peaceful rasboras, pencilfish, Corydoras, peaceful loricariid catfish and smaller, non-aggressive South American cichlids such as keyhole cichlids. They are best housed with fish that appreciate warm, clean, well-oxygenated water. Avoid large predatory fish, highly aggressive cichlids and persistent fin-nippers, which may harass or eat them. Very tiny, slow-moving species may also be unsettled by their constant activity.

Red Tail Hemiodus Tetras are egg-scattering fish and are rarely bred in home aquariums. A separate breeding aquarium with soft, slightly acidic water, subdued lighting and fine-leaved plants or spawning mops may encourage spawning. Adults should be removed after spawning because they may eat the eggs. The eggs generally hatch within a few days, and the tiny fry require appropriately sized first foods such as infusoria before progressing to newly hatched brine shrimp.

Females are generally fuller-bodied, particularly when carrying eggs, while males tend to be slimmer. Clear external differences are subtle, and sexing young Red Tail Hemiodus Tetras can be difficult.