Overview
The Flame Tetra, also widely known as the Red of Rio (Hyphessobrycon flammeus), is a staple in the aquarium hobby. The "DNZ" designation often indicates "Deutsche Nachzucht," meaning these specimens are captive-bred in Germany, ensuring they are hardy, adapted to aquarium conditions, and environmentally sustainable. Known for their striking coloration and dynamic schooling behavior, they are a fantastic addition to planted community tanks.
Distribution and Habitat
In the wild, the Flame Tetra originates from South America, specifically the coastal river drainages of Rio de Janeiro, Brazil. They naturally inhabit slow-moving rivers, streams, and tributaries heavily shaded by dense forest canopies. These waters are typically stained with tannins from decaying organic matter, creating a slightly acidic, soft water environment with plenty of submerged roots and vegetation.
Description of Flame Tetra

The Flame Tetra is aptly named for its brilliant, fire-like coloration that develops as the fish matures and settles into a comfortable environment.
Body shape:
They possess a classic tetra profile: laterally compressed, somewhat deep-bodied, and roughly diamond-shaped, allowing them to navigate easily through dense aquatic vegetation.
Color:
The anterior (front) half of the body is typically a shimmering silver or olive-green, which abruptly transitions into a vibrant, fiery red towards the posterior. They feature two distinct, vertical black bars just behind the gills.
Barbels:
Like other characins, the Flame Tetra does not possess any barbels.
Snout:
The snout is relatively short and blunt, featuring a small, terminal mouth designed for snatching small insects and zooplankton from the water column.
Eyes:
They have proportionally large, alert eyes with a dark pupil and a highly reflective, often silvery-blue iris, which aids in low-light vision.
Fins:
The dorsal, anal, and pelvic fins are a striking bright red. In males, the anal fin is often edged in black, and the pelvic fins may display white tips.
The Tail:
The caudal (tail) fin is deeply forked. While mostly transparent to aid in stealth, the base of the tail often carries the red pigment from the body.
Temper
Flame Tetras are incredibly peaceful and timid by nature. They do not nip fins or harass other tank mates, making them model citizens for a tranquil community aquarium.
Sociality
This species is highly gregarious and must be kept in a school to feel secure. A minimum group of 6 to 8 individuals is required, though schools of 12 or more will encourage their best colors and most natural behaviors.
Activity
They are highly active mid-water swimmers. When kept in proper numbers, they will constantly dart around the middle levels of the aquarium, occasionally breaking formation to explore plants before regrouping.
Keeping and Caring for Flame Tetra
Because the "DNZ" (captive-bred) strains are far removed from their wild ancestors, they are highly adaptable and very forgiving of minor fluctuations, making them an excellent choice for beginners.
Tank size:
A minimum tank size of 60 liters (15 gallons) is recommended to provide adequate swimming space for a small school, though a 20-gallon long is ideal.
Water Parameters:
While adaptable, mimicking their natural habitat will yield the brightest colors and longest lifespans.
Temperature
They thrive in standard tropical temperatures between 22-28°C (72-82°F).
pH
A slightly acidic to neutral pH ranging from 5.8 to 7.5 is ideal.
Hardness
Soft to moderately hard water is acceptable, ideally between 3 and 15 dGH.
Ammonia, Nitrite, Nitrate
Ammonia and Nitrite must always remain at 0 ppm. Nitrates should be kept below 20 ppm through regular water changes and plant filtration.
Lighting
Moderate to dim lighting is preferred. High-intensity lighting can wash out their colors and cause stress unless the tank is heavily shaded by floating plants.
Water flow
A gentle water flow is best, simulating the sluggish streams of their native habitat.
Decorations and Plants
A dark substrate will beautifully contrast their red coloration. The tank should be heavily planted with species like Amazon Swords, Cryptocorynes, and Java Fern, alongside driftwood and leaf litter to provide hiding spots and release beneficial tannins.
Diet
Flame Tetras are omnivorous micro-predators. In the aquarium, they will readily accept high-quality crushed flakes and micro-pellets. To ensure optimal health and vibrant reds, supplement their diet with live or frozen foods like daphnia, baby brine shrimp, and bloodworms.
Some Feeding Tips
Feed them small amounts once or twice a day—only what they can consume in under two minutes. Because they have small mouths, ensure that all prepared foods are appropriately sized.
Breeding
Breeding the Flame Tetra is relatively straightforward. They are egg-scatterers that exhibit no parental care. To breed them, set up a separate dimly lit breeding tank with soft, slightly acidic water and line the bottom with fine-leaved plants like Java Moss or a spawning mop. Condition the breeders with live foods. Spawning usually occurs in the morning. Once eggs are scattered, the parents must be removed immediately to prevent them from eating the eggs. The fry will hatch in 24-36 hours and become free-swimming a few days later, requiring infusoria or liquid fry food initially.
Conclusion
The Flame Tetra (Red of Rio) is a true gem of the aquarium hobby. With its undemanding nature, peaceful temperament, and striking contrast of silver, black, and fiery red, it is an ideal choice for aquarists of all skill levels looking to add life and color to a planted community tank.
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