Neon tetra
The best-known aquarium fish in the world, and one of the most frequently misjudged. Neons are commercially bred in enormous numbers, which has made them cheap but not hardy — farmed stock is notably less robust than the species' reputation suggests, and losses in the first weeks after purchase are common.
Quick profile
- Scientific name
- Paracheirodon innesi
- Adult size
- 3–3.5 cm (1.2–1.4 in)
- Lifespan
- 3–5 years
- Temperature
- 20–26 °C (68–79 °F)
- pH
- 4–7.5
- Hardness
- 1–10 °dGH
- Minimum tank
- 60 L (16 US gal)
- Minimum length
- 60 cm
- Swimming zone
- Midwater
- Social
- Schooling — at least 8
- Diet
- Micropredator
- Overall confidence
- high confidence
What keeping this species involves
Undemanding once settled, but intolerant of an uncycled tank and of the sharp parameter changes that happen in a newly set-up aquarium. It is a poor first fish for a tank that has not finished cycling.
Shaded blackwater and clearwater tributaries with heavy leaf litter, low mineral content and dim light filtered through overhanging forest.
Identity and names
- Common name
- Neon tetra
- Scientific name
- Paracheirodon innesi
- Family
- Characidae
- Order
- Characiformes
- Class
- Actinopterygii
- Also sold as
- neon, neons, tetra neon
Adult size and growth
3–3.5 cm (1.2–1.4 in) — Farmed stock often stops slightly short of wild size.
Typical lifespan in an aquarium: 3–5 years. Almost every animal sold in a shop is a juvenile, so the tank has to suit the size in the first line rather than the size in the bag.
Water and tank requirements
A shoal of eight needs continuous horizontal swimming space; 60 cm is the shortest tank in which the group can move as a group rather than turning constantly.
| Requirement | Value | Notes |
|---|---|---|
| Temperature | 20–26 °C (68–79 °F) | Stability matters more than hitting an exact figure. |
| pH | 4–7.5 | A stable pH outside the ideal band is usually better than an unstable one inside it. |
| General hardness | 1–10 °dGH | Check your supplier's published figure before choosing species. |
| Minimum volume | 60 L (16 US gal) | A floor, not a recommendation. |
| Minimum footprint | 60 cm long | A shoal of eight needs continuous horizontal swimming space; 60 cm is the shortest tank in which the group can move as a group rather than turning constantly. |
| Water flow | low | Match the outflow to this rather than to the filter's rating. |
| Lid required | Recommended | Reduces evaporation and prevents accidents. |
Behaviour
- Schools tightly when startled and disperses loosely when relaxed — a tight, motionless school in daylight usually means something is wrong.
- Occupies the middle of the water column and rarely uses the surface.
Telling males from females
Females are deeper-bodied; the blue stripe often looks slightly bent in gravid females.
Feeding
Mouth is genuinely small; standard flake often needs crushing.
- Diet type
- Micropredator
- Staples
- Small dry foods, Frozen daphnia, Baby brine shrimp, Micro-worm
Breeding
- Strategy
- Egg-scattering in very soft, acidic, dim water
- Difficulty
- challenging
- Parental care
- none
Eggs are light-sensitive and the fry are tiny. Commercial production uses conditioned water that most home tanks do not replicate.
Tankmates and compatibility
Assessments are derived from stored traits by the compatibility engine, with the reasoning shown. A verdict is a statement about probability, not a guarantee — individual temperament can override it.
| Towards | Risk | What it means |
|---|---|---|
| Small fish | none | Anything that fits in the mouth is at risk once this species reaches adult size. |
| Adult dwarf shrimp | none | Cover reduces losses but rarely prevents them where the risk is high. |
| Shrimplets | moderate | Determines whether a shrimp colony can grow rather than merely persist. |
| Snails | none | Applies to snails you wanted as well as snails you did not. |
| Long or trailing fins | none | Fin damage is an entry point for secondary infection. |
| Plants | none | Tough species such as Anubias and Java fern survive most grazers. |
Assessed pairings
Any pair in the catalogue can be assessed with the compatibility checker.
Welfare considerations
Points where the way this species is commonly sold or kept differs from what it actually needs.
- Neon tetra disease (Tetrahymena-associated) is untreatable and spreads within a group; the practical response is separation, not medication.
- Colour loss and hiding are the earliest signs of stress and appear well before any physical sign.
Problems to watch for
Most problems in a tank containing this species are general rather than species-specific. Start with the troubleshooting index and work from the observation rather than from a guess at the cause.
What AquariumHQ does not yet hold
Species-level disease susceptibility is modelled in the graph and is not yet populated. Health pages will not be published until each condition has veterinary sourcing, because health content written without evidence is the most harmful thing this product could publish. The gap is recorded in the coverage report.
Where it comes from
- Native range
- Upper Amazon basin — Peru, western Brazil and south-eastern Colombia
- Habitat
- Shaded blackwater and clearwater tributaries with heavy leaf litter, low mineral content and dim light filtered through overhanging forest.
What the checklists say
14 distribution statements retrieved from GBIF checklists. Establishment means is reproduced from the source where it states one, and left unstated where it does not — a record of presence is not a record of origin.
| Status | Places | What this means |
|---|---|---|
| Native | 3 | A checklist states the species occurs here naturally. |
| Introduced | 6 | A checklist states the species arrived here with human help. That is not a statement that it is established, harmful or illegal. |
| Recorded as present, establishment means not stated | 5 | The source records the species as present and does not say whether it is native or introduced. AquariumHQ does not fill that in. |
Evidence
Every stored value with the kind of support behind it and where to check it. Evidence type and confidence are separate axes: an editorial position held confidently and a measurement held tentatively are different things.
| Claim | Value | Evidence type | Confidence | Source |
|---|---|---|---|---|
| scientific name | Paracheirodon innesi | Observed / measured | high confidence | Catalogue of Life; GBIF — Global Biodiversity Information Facility |
| native range | Upper Amazon basin — Peru, western Brazil and south-eastern Colombia | Observed / measured | moderate confidence | GBIF — Global Biodiversity Information Facility |
| adult size | 3–3.5 cm | Aquarium-literature consensus | high confidence | AquariumHQ husbandry synthesis |
| lifespan | 3–5 years | Aquarium-literature consensus | high confidence | AquariumHQ husbandry synthesis |
| temperature | 20–26 °C | Aquarium-literature consensus | high confidence | AquariumHQ husbandry synthesis |
| ph | 4–7.5 pH | Aquarium-literature consensus | high confidence | AquariumHQ husbandry synthesis |
| general hardness | 1–10 °dGH | Aquarium-literature consensus | high confidence | AquariumHQ husbandry synthesis |
| minimum tank volume | ≥ 60 L | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank length | ≥ 60 cm | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum group size | ≥ 8 | AquariumHQ editorial position | high confidence | AquariumHQ husbandry synthesis |
Last reviewed 2026-08-10. Values labelled as an aquarium-literature consensus are AquariumHQ editorial positions rather than measurements — see how evidence is handled.
Why we say this
What each figure on this page rests on, and how far that is from being independently established.
Every figure on this page has a provenance. Open any claim to see what AquariumHQ holds for it, which sources say what, and what a claim of that kind actually needs. Different claims need different evidence: an accepted scientific name is settled by one authority, while a legal restriction needs a current primary instrument. A single source is often the right answer rather than a thin one.
scientific nameAquariumHQ's own position, externally checkableBased on a verified authoritative source.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: accepted scientific name and classification — 1 authoritative source in an appropriate context. Checked against gbif on 2026-08-11. One authoritative backbone is what this class requires.
What would improve this: Go and read a source. This is reachable and has not been reached.
native rangeAquariumHQ's own position, externally checkableBased on a verified authoritative source.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: where the species occurs — 1 authoritative source in an appropriate context. 14 distribution statements held from GBIF checklists — native in 3, introduced in 6 countries. Establishment means is reproduced from the source, never inferred from occurrence.
What would improve this: Go and read a source. This is reachable and has not been reached.
adult sizeOne sourceBased on a verified authoritative source.1 citation, 1 independent origin
A single source: fishbase.
- 2.5–2.5 cm — FishBase · Maximum recorded · The range the species is recorded from · checked 2026-08-11
What this kind of claim needs: size a well-kept specimen reaches — no external source is required, provided AquariumHQ shows its reasoning. One authoritative source, which is what this kind of claim requires. Independent replication would be welcome and is not the standard.
What would improve this: Corroborate against a second, independent source.
lifespanAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
temperatureIndependently verifiedConfirmed by more than one independent source.2 citations, 2 independent origins
2 citations from 2 independent origins.
- 21–25 °C — AquariumHQ husbandry synthesis · Recommended for keeping · Recommended for keeping · checked 2026-08-11
- 20–26 °C — FishBase · Tolerated range · The range the species is recorded from · checked 2026-08-11Corrected on checking from 20–28 °C.
- 22–27 °C — Ornamental Aquatic Trade Association · Recommended for keeping · Recommended for keeping · checked 2026-08-11Corrected on checking from 20–26 °C.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. 2 independent origins.
What would improve this: Nothing. Recheck when the sources are next reviewed.
phAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
general hardnessAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
minimum tank volumeAquariumHQ's judgement — no authority publishes thisAquariumHQ's own position, derived from evidenced inputs.
No external authority publishes this. The rationale carries the reasoning.
What this kind of claim needs: minimum tank size — no external source is required, provided AquariumHQ shows its reasoning. No authority publishes this. AquariumHQ derives it, and the derivation is recorded with its inputs and assumptions.
What would improve this: Keep the rationale current. There is no source to find.
minimum tank lengthAquariumHQ's judgement — no authority publishes thisAquariumHQ's own position, derived from evidenced inputs.
No external authority publishes this. The rationale carries the reasoning.
What this kind of claim needs: minimum tank size — no external source is required, provided AquariumHQ shows its reasoning. No authority publishes this. AquariumHQ derives it, and the derivation is recorded with its inputs and assumptions.
What would improve this: Keep the rationale current. There is no source to find.
minimum group sizeAquariumHQ's judgement — no authority publishes thisAquariumHQ's own position, derived from evidenced inputs.
No external authority publishes this. The rationale carries the reasoning.
What this kind of claim needs: group size — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Keep the rationale current. There is no source to find.
Group size and social behaviour
An obligate schooling species. In groups below about eight, neons stop schooling, spend more time hidden and lose colour — the blue stripe dulls markedly under stress, which makes it a useful welfare indicator.