Black neon tetra guide

Common name: Black neon tetra
Scientific name: Hyphessobrycon herbertaxelrodi
Category: Freshwater fish
Group: Tetras and characins
Environment: Mature freshwater aquarium with open mid-water swimming space, planted or wooded shade and stable clean water
Origin: Upper Paraguay River basin in central Brazil, especially Mato Grosso and Mato Grosso do Sul
Care level: Beginner to intermediate
Adult size: Up to 3.2 cm standard length; approximately 4 cm total length
Expected lifespan: Plan for approximately 5–8 years and potentially longer under stable schooling care.
Minimum housing: At least 80 L with a 75 cm or longer footprint for a group of ten or more
Temperature: 20–28 °C
pH: 5.0–7.5
Hardness / minerals: 18–179 mg/L as CaCO₃, approximately 1–10 dGH
Salinity: Freshwater, 0 ppt; routine salt addition is not recommended
Lighting: Subdued to moderate, with shaded planted margins
Placement / zone: Middle water
Filtration: Use mature biological filtration sized for the complete adult black neon tetra group, with guarded intakes and accessible mechanical capture. Keep flow gentle to moderate with open midwater lanes and dependable surface exchange where the fish lives, and maintain undetectable ammonia and nitrite.
Aeration: Maintain reliable surface agitation and oxygen exchange at all times. Increase aeration during warm weather, medication, transport recovery, heavy feeding or any sign of rapid breathing.
Maintenance: Perform regular matched-water changes guided by nitrate and waste, remove uneaten food and trapped detritus, clean mechanical media without disrupting the biofilter, and record feeding, body condition, respiration and aggression.

Identity and search names

Single-species profile for Hyphessobrycon herbertaxelrodi. Despite the common name, it is not a Paracheirodon neon tetra; the pale upper stripe and dark lateral band identify a different lineage.

Search names: Black neon, Herbert Axelrod’s tetra

Environment and housing

Provide a long open swimming lane, dark substrate, plants or wood at the margins, gentle to moderate flow and mature filtration

Social structure: Keep at least ten; larger groups show better colour, coordination and confidence

Feeding and nutrition

Feeding ecology: Small omnivore and micropredator taking tiny invertebrates, zooplankton and fine prepared foods

Feeding routine: Feed two or three small meals daily and spread food across the school

Breeding, reproduction or spread

Egg scatterer without parental care; adults eat eggs and should be removed from a dedicated spawning aquarium

Detailed care and app-ready planning

Identity scope: Single-species profile for Hyphessobrycon herbertaxelrodi. Despite the common name, it is not a Paracheirodon neon tetra; the pale upper stripe and dark lateral band identify a different lineage.
Adult size and space: Adults reach 3.2 cm standard length, roughly 4 cm total length. Use at least 80 L with 75 cm or more of frontage for ten or more fish.
Social structure: Maintain at least ten, preferably more. A larger school improves confidence and distributes brief chasing and courtship activity.
Swimming zone or placement: Middle water, moving between open lanes and shaded plant or wood margins.
Feeding ecology: A small omnivore and micropredator taking tiny insects, crustaceans and zooplankton in addition to fine plant and detrital material.
Feeding plan: Offer fine flakes or micro-pellets and small frozen invertebrates two or three times daily. Scatter food over a broad area so every fish feeds.
Water stability: Maintain 20–28 °C, pH 5.0–7.5 and about 1–10 dGH with zero ammonia and nitrite, low nitrate and no rapid temperature or chemistry change.
Habitat structure: Use a dark substrate, planted or wooded margins, floating shade, open mid-water space and gentle to moderate circulation.
Compatibility plan: Choose peaceful small tetras, rasboras, corydoras and similar fish with matching water needs. Avoid predators, aggressive fin-nippers and hyperactive feeders.
Breeding or reproduction plan: Condition adults, place a pair or small group in a separate dim spawning aquarium with fine plants or mesh, then remove adults because eggs are eaten. Fry require microscopic first foods.
Quarantine: Quarantine in a separate cycled freshwater aquarium with dedicated nets, containers and siphons. Match temperature and mineral chemistry gradually, confirm normal feeding, respiration, skin, fins and waste, and never pour transport water into the established aquarium.
Welfare checks: Check school cohesion, colour, body weight, fin edges, respiration, normal mid-water use and whether every fish feeds promptly.
Biosecurity and release: Never release fish, fry, eggs, aquarium water, sediment, plants or foods into drains, dams or natural waterways. Check the exact accepted scientific name in current BICON and applicable South Australian rules before import, sale or movement; import eligibility does not authorise release or wild collection.
Main risk: An undersized school or cramped aquarium creates chronic fear and weak feeding even when water tests appear acceptable.
Adult projected load: Project biological load from the full adult black neon tetra group, adult body mass, feeding pattern, activity and social requirement rather than juvenile sale size. A proper school has moderate combined biomass and repeated small-food demand; under-grouping concentrates stress and weak feeding.
Filtration: Use mature biological filtration sized for the complete adult black neon tetra group, with guarded intakes and accessible mechanical capture. Keep flow gentle to moderate with open midwater lanes and dependable surface exchange where the fish lives, and maintain undetectable ammonia and nitrite.
Aeration: Maintain reliable surface agitation and oxygen exchange at all times. Increase aeration during warm weather, medication, transport recovery, heavy feeding or any sign of rapid breathing.
Maintenance: Perform regular matched-water changes guided by nitrate and waste, remove uneaten food and trapped detritus, clean mechanical media without disrupting the biofilter, and record feeding, body condition, respiration and aggression.
Overridable warnings: Non-overridable: do not accept persistent ammonia or nitrite, oxygen distress, starvation, chronic aggression or inadequate adult space. Different equipment, stocking or maintenance methods may be used only when measured water quality and adult welfare remain equivalent or better. A group of ten or more and enough swimming length cannot be overridden by small individual body size.

Compatibility, welfare and risk

Compatibility: Keep with small peaceful fishes sharing the same water range and unlikely to swallow or intimidate the school

Welfare: Monitor schooling, colour, belly fullness, fin condition, respiration and feeding access; a fish repeatedly isolated from the group requires immediate investigation.

Main warning: Six fish is a bare social minimum, not a target. A group of ten or more and adequate horizontal room produce more normal schooling and feeding behaviour.

Biosecurity and release

Never release fish, fry, eggs, aquarium water, sediment, plants or foods into drains, dams or natural waterways. Check the exact accepted scientific name in current BICON and applicable South Australian rules before import, sale or movement; import eligibility does not authorise release or wild collection.

Black neon tetra