Neon tetras (Paracheirodon innesi) are small, peaceful schooling fish that come from blackwater Amazonian tributaries. They look and act best when kept in an appropriate group in a mature aquarium with gentle water flow and plenty of cover.
Quick answers (the answers most people want to know)
- Minimum tank size: 10 gallons / ~38–40 L for a small school; 20 gallons / ~75 L+ will be noticeably better.
- Temperature: 22–26°C (72–79°F) Stability is more important than "perfect."
- pH: 6.0–7.0 Slightly acidic to neutral.
- Group size: Absolute minimum 6, but 10–12+ are strongly recommended.
Minimum tank size (what “minimum” really means)
Many care guides list 10 gallons (~38–40 L) as the minimum for a small group.
In practice, a larger tank (15–20 gallons / 55–75 L+) is easier for beginners because:
- water parameters swing less,
- the school can move naturally,
- you have room for plants and calm tankmates without crowding.
Rule of thumb: if you want the classic “tight school” look, plan for 10–20+ neons and size the tank accordingly (longer tanks help more than taller tanks).
Temperature (°C/°F)
A solid everyday target is 22–26°C (72–79°F).
Avoid rapid changes—neons are more sensitive to instability than to being 1–2 degrees off the “ideal.”
Tip: keep temperature consistent with a reliable heater; avoid strong heater/fan cycling.
pH (and why stability beats chasing numbers)
Most common guidance for neon tetras is pH 6.0–7.0.
If your tap water is slightly outside this but stable, you can usually keep neon tetras successfully—especially captive-bred fish—by prioritizing:
- consistent maintenance,
- avoiding sudden parameter changes,
- good filtration and low ammonia/nitrite (always 0).
Group size (schooling behavior)
Neon tetras are schooling fish. Keeping too few often leads to:
- hiding,
- stress,
- duller colors,
- more fin-nipping within the group.
Most guidance says minimum 6, but larger groups look better and behave more naturally; some guides explicitly recommend 12+ for best results.
Best practice:
- Beginner-friendly: 8–12
- “Wow” schooling: 12–20+ (with enough tank length and filtration)
Setup checklist (fast but important)
- Tank maturity: add neons only after the tank is cycled and stable (they’re not ideal “first fish”).
- Filtration/flow: gentle to moderate flow; avoid blasting currents.
- Decor: plants + driftwood + darker substrate helps them feel secure and show better color.
- Tankmates: choose peaceful fish; avoid aggressive or fin-nippy species.
FAQ
Can I keep 4 neon tetras?
Not recommended. They’re likely to be stressed and hide. Aim for 6 minimum, ideally 10+.
Is 10 gallons enough long-term?
It can work for a small school, but 20 gallons is easier and gives better schooling behavior and stability.