Common Name: Red Tail Hemiodus
Scientific Name: Hemiodus gracilis
Other Names: Slender Hemiodus, Red Tail Hemiodont
The Red Tail Hemiodus is a sleek and fast-moving schooling fish known for its elongated body, shimmering silver coloration, and striking red caudal fin. This species is highly active and requires ample swimming space, making it a great choice for larger aquariums with other mid-to-upper water column swimmers. Unlike some of its relatives, Hemiodus gracilis is less prone to jumping but still benefits from a well-secured tank cover.
Habitat and Distribution:
Native to the Amazon and Orinoco River basins in South America, Hemiodus gracilis inhabits clearwater and blackwater rivers, as well as flooded forest areas. It prefers open water with moderate to strong currents, often schooling in large numbers to avoid predation. The water in its natural habitat is warm, well-oxygenated, and slightly acidic to neutral.
Size and Lifespan:
This species grows to about 6-8 inches (15-20 cm) in captivity. With proper care, it can live for 5-8 years.
Diet and Behavior:
The Red Tail Hemiodus is an omnivore that primarily feeds on small invertebrates, insect larvae, and plant matter in the wild. In captivity, it should be fed a varied diet of high-quality flake or pellet food, supplemented with frozen or live foods such as brine shrimp, daphnia, and bloodworms, as well as occasional plant-based foods like spirulina flakes. It is a peaceful, fast-moving schooling fish that must be kept in groups of at least six to reduce stress and encourage natural behaviors.
Breeding and Reproduction:
Breeding Hemiodus gracilis in captivity is extremely rare, as they require specific environmental conditions and a large open-water setup to trigger spawning. They are egg scatterers, with little to no parental care. Most specimens in the aquarium trade are wild-caught.
Aquarium Care and Tank Requirements:
A minimum of 75 gallons is required for a school, with a larger tank (100+ gallons) recommended for optimal swimming space. Their ideal tank setup includes a fine sand or smooth gravel substrate, open swimming areas with some driftwood or rock structures, strong filtration with high oxygenation, moderate to strong water flow to replicate their natural environment, and dim to moderate lighting to reduce stress.
Ideal Tank Mates:
The Red Tail Hemiodus is peaceful and does well in community tanks with other fast-moving, similarly sized fish. Suitable tank mates include Silver Dollars, Larger Tetras, Geophagus Cichlids, Severums, Corydoras Catfish, and Peaceful Plecos. Avoid slow-moving or long-finned fish, as their rapid swimming may cause stress.
Difficulty Level:
Intermediate. They require a large, well-oxygenated tank with stable water parameters and a high-energy diet to thrive.
Water Parameters:
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Temperature: 75-82°F (24-28°C)
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pH: 6.0-7.5
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General Hardness (GH): 4-12 dGH
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Carbonate Hardness (KH): 3-8 dKH
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Ammonia: 0 ppm
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Nitrite: 0 ppm
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Nitrate: <20 ppm (regular water changes required)
Additional Information:
- A strong current is beneficial, as they originate from fast-moving waters.
- A secure lid is recommended, as they may jump when startled.
- Keeping them in groups reduces stress and enhances their natural schooling behavior.
The Red Tail Hemiodus is an elegant and energetic fish that brings movement and vibrancy to larger community aquariums. With the right setup and care, they make a rewarding addition to South American biotope tanks.
