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Black neon tetra

Hyphessobrycon herbertaxelrodi

Not a 'black neon' but a completely different fish from the classic neon: two horizontal stripes — one iridescent white above and one velvety black below — run along the silver body, creating a hypnotic graphic contrast. The eye iris is ruby red, a distinctive detail. Native to South America's Paraguay basin. One of the most robust and long-lived tetras, perfect for beginners. In schools of 10+ on dark substrate with dim lighting, the visual effect of aligned stripes is professional-grade. Lid recommended: may jump.

Taxonomy
Class:Actinopteri
Order:Characiformes
Family:Characidae
Genus:Hyphessobrycon
Species:Hyphessobrycon herbertaxelrodi

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Water Temperature

23 - 27 °C

pH Value

5.5 - 7

Water type

Freshwater

Tank level

Middle

Adult size

4 cm

Minimum tank volume

>= 75 L

Minimum group

>= 6

GH

1 - 10 dGH

KH

0 - 14 dKH

TDS

15 - 290 ppm

Conductivity

23 - 453 uS/cm

Species description

Geographical Origin and Habitat: Rio Paraguay Basin (Mato Grosso). Swims in still or very slow waters, dark (Igapó) or clear but still densely shielded by marginal plants.
Taxonomy and Morphology: Black Neon Tetra (Hyphessobrycon herbertaxelrodi). Not a true Neon (genus Paracheirodon), but a taller and more compact cousin of the Hyphessobrycon clade. Characteristic large eye.
Social Behavior: Strictly schooling (10+). If kept in small numbers it becomes shy or stressed. In large schools it swims in an hypnotic and compact manner in the medium-high range.
Coloration and Sexual Dimorphism: Olive-gray background with two longitudinal bands side by side: a superior iridescent greenish-white/golden one and a thick velvety black inferior one. Bright red upper iris. Females are noticeably more swollen.

Care, breeding and tankmates

Aquarium Setup: Seeks dark contrasts. Black gravel or dark bottom and dim lighting (or abundant floating plants) are a must to make the iridescent line light up; on white backgrounds it fades enormously.
Diet and Feeding: Omnivore (Micro-predator). Feeds at the surface or in mid-water, ignoring remains on the bottom. Crumbled flakes, live brine shrimp and frozen bloodworms are perfect.
Water Quality: Very resistant for a "Neon", tolerates treated tap water well, but prefers slightly acidic water (pH 6.5) for full health and coloration.
Compatibility and Cohabitation: The perfect choice for a peaceful Amazonian tank. Ideal with Discus (does not fear warm temperatures unlike classic Neons), Angelfish (if large enough not to be eaten), and Loricariids.
Aquarium Breeding: Moderately difficult Egg-scatterer. Spawns in groups on dense mosses; eggs hatch in 24 hours. The use of a net on the bottom of the breeding tank saves the eggs from hungry parents.
Risks and Diseases: Less prone to Neon Tetra Disease (Pleistophora) than the classic Neon, but sensitive to Ichthyophthirius (White spots) in case of cold thermal shocks.

Geographic Origin and Distribution

Rio Paraguay Basin (Mato Grosso). Swims in still or very slow waters, dark (Igapó) or clear but still densely shielded by marginal plants.

Origin

Extra-Amazon South America

Fish profile

Temperament
Peaceful
The Hyphessobrycon herbertaxelrodi is renowned for its peaceful, albeit somewhat shy and timid, temperament. They are highly social fish that absolutely depend on the presence of a sizable school for their confidence and well-being. When kept in sufficient numbers, they exhibit a lively and inquisitive nature, gracefully exploring the aquarium. However, if kept alone or in very small groups, they will likely become withdrawn, pale, and prone to hiding constantly.
Diet
Omnivore
In its natural habitat, the Hyphessobrycon herbertaxelrodi is a micro-predator that primarily feeds on tiny invertebrates and zooplankton. In captivity, they eagerly accept a staple diet of high-quality crushed flakes and micro-pellets. To support their overall health and promote optimal development—such as their striking neon green and black horizontal bands—their diet should be frequently supplemented with live or frozen foods like Daphnia and cyclops. A diverse nutritional profile is crucial for maintaining a robust immune system.
Sex ratio
School
When establishing a school of Hyphessobrycon herbertaxelrodi, maintaining a relatively balanced mix of males and females is beneficial. Males generally exhibit a slimmer profile and often display their characteristic black and white lateral stripes more intensely compared to the plumper females. Having slightly more females than males can help dissipate any minor intra-species sparring when males display for dominance. Ultimately, keeping a large enough overall group size is more critical than the exact sex ratio.
Feeding frequency
Twice daily
For optimal health, the Hyphessobrycon herbertaxelrodi should be fed small portions two to three times a day. Only offer an amount of food that the school can completely consume within two minutes to prevent water fouling. Overfeeding is a common issue with small characins, so strict portion control must be maintained. This frequent, small-meal approach closely mimics their continuous foraging behavior in the wild.
Bioload
Low
The Hyphessobrycon herbertaxelrodi contributes a very low bioload to the aquarium ecosystem due to its small size. This makes them highly suitable for densely planted nano tanks and community setups alike. Despite their low waste production, maintaining a strict schedule of weekly water changes is highly recommended. A standard, high-quality biological filtration system will easily process the minimal waste generated by a healthy school.
Flow
Strong
The Hyphessobrycon herbertaxelrodi naturally inhabits slow-moving streams and flooded forest areas, meaning they prefer gentle water flow in the aquarium. Strong currents from overpowered filters can quickly exhaust these small fish and cause chronic stress. A sponge filter or a baffled hang-on-back filter is usually the most appropriate choice to provide oxygenation without turbulent flow. Providing dense clusters of aquatic plants will also give them tranquil resting spots.
Jump risk
Yes
Like many similarly sized characins, the Hyphessobrycon herbertaxelrodi presents a moderate jumping risk, especially when initially introduced or startled. A secure, tight-fitting aquarium lid or a glass canopy is absolutely essential to prevent accidental losses. Employing floating plants such as Salvinia or Amazon Frogbit can provide overhead cover, which significantly reduces their skittishness. Stable water parameters and a peaceful environment will also minimize this leaping behavior.
Reproduction
Oviparous
Breeding the Hyphessobrycon herbertaxelrodi requires a separate, dimly lit breeding tank equipped with soft, slightly acidic water. They are typical egg-scatterers that exhibit no parental care whatsoever, and they will readily consume their own eggs if left in the breeding tank. Spawning typically occurs among fine-leaved plants, after which the adults must be immediately removed. The microscopic fry require infusoria or specialized liquid foods until they are large enough to eat freshly hatched brine shrimp.
Compatibility & tankmates
Peaceful
As a peaceful schooling species, the Hyphessobrycon herbertaxelrodi thrives when kept in a vibrant community aquarium. They require the security of a group, so maintaining them in schools of at least eight individuals is essential. Excellent tank mates include small rasboras, Corydoras catfish, and other equally peaceful characins. Aggressive, large, or excessively boisterous fish should be strictly avoided to prevent them from becoming stressed or preyed upon.
Tank level
Middle
The Hyphessobrycon herbertaxelrodi is an active swimmer that primarily occupies the mid to upper levels of the aquarium water column. They deeply appreciate having a large, open swimming space in the center of the tank to school properly. They will often dart around the middle strata during the day, occasionally diving to the substrate during feeding times. Tall background plants and floating vegetation help them feel secure in these preferred swimming zones.

Window to the official scientific data of the species

Data synced on: 06/15/2026

Scientific Parameters & Models

Trophic level
2.9 ± 0.31 se
Resilience
High (less than 15 months)
Phylogenetic uniqueness (PD50)
0.5
Bayesian Length-Weight
a = 0.01202, b = 3.09
VulnerabilityLow vulnerability (10 / 100)

Image gallery

Licensed images linked to the species or, when marked, to the closest representative taxon.

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Last updated: 06/30/2026
Black neon tetra (Hyphessobrycon herbertaxelrodi) Care Guide & Tank Setup | Atlarium