Neon tetra

Quick facts

Adult size

4 cm

Lifespan

can live up to 8 years; captive average is 3-5 in well-maintained tanks

Tank zone

mid

Temperament

peaceful

Difficulty

beginner

Schooling

recommended 6+ (critical minimum 4, thrives at 10+)

Water parameters

Temperature

22–26°C

pH

5.0 to 7.5

Hardness

1 to 10 dGH

Tank requirements

Minimum volume

75 L

Minimum length

60 cm

Flow

low

Lighting

dim preferred

Substrate

any

Driftwood

preferred

Hiding spots

needed

Feeding

Diet: omnivore, feeds primarily at the mid.

Small mouths limit food size. Micro pellets, crushed flake, and frozen daphnia or baby brine shrimp are staples. Frozen bloodworm is accepted but chop it first; whole bloodworms are too large for most neons to swallow. Feed small amounts twice daily rather than one large feeding. Neons are midwater feeders and generally ignore food that sinks to the bottom, so pair them with bottom feeders like corys to clean up leftovers.

Compatibility

• Stressed by aggressive or boisterous tankmates, even non-predatory species. Tiger barbs and serpae tetras cause constant fin damage.
• Classic community fish with corydoras, small rasboras, honey gouramis, and other calm species. Avoid anything large enough to eat them (angelfish will, despite being sold alongside neons in stores).
• Adult neons may pick at very small shrimp fry but ignore adult cherry shrimp and amano shrimp.
• Susceptible to neon tetra disease (Pleistophora hyphessobryconis), which is incurable and contagious. Quarantine all new neons for 2-3 weeks before adding to an established group.

Habitat

Native to soft, acidic blackwater tributaries of the Amazon basin in Brazil, Peru, and Colombia. Wild populations live in streams stained dark by tannins, where pH drops below 5.0 and hardness is near zero. Modern commercial stock is tank-bred (mostly in Southeast Asian farms) and tolerates a much broader range than wild fish, handling pH 6.0-7.5 and moderate hardness without issue. The iridescent blue-red stripe is structural color from guanine crystals, not pigment, which is why it looks different under different lighting angles. Groups of 10+ in a planted tank with subdued lighting bring out the best color and behavior. They school tightly when nervous and spread out when relaxed, which is a useful stress indicator.

Breeding

Egg scatterer. Breeding in a home aquarium is possible but tricky. Requires very soft acidic water (pH 5.5, GH below 2), dim lighting, and a separate breeding tank with fine-leaved plants or spawning mops. Condition the pair with frozen food for a week. Spawning usually happens at dawn. Eggs are light-sensitive and the parents will eat them immediately, so remove the adults right after spawning. Eggs hatch in about 24 hours; fry are tiny and need infusoria for the first week, then baby brine shrimp. Most hobbyists never breed neons because the water parameters required are difficult to maintain, and commercially bred neons cost almost nothing.

Common problems

Neon tetra disease is the signature ailment: loss of color, cysts in the muscle tissue, erratic swimming, and eventual death. There is no cure and it spreads to other neons. Remove affected fish immediately. "False neon tetra disease" (bacterial) looks similar but responds to antibiotics. Ich is common in newly purchased neons that were stressed during transport. Quarantine and treat with heat (30°C for 3 days) or medication. Neons are sensitive to ammonia and nitrite spikes; they're often the first fish to show stress in an uncycled tank, which is why "my neons keep dying" is one of the most common beginner questions. The answer is almost always water quality.

Bioload

Bioload coefficient: 1.0 (reference species; all other bioload coefficients are calibrated against this).

Bioload coefficients are calibrated against the neon tetra as the anchor (1.0). See the methodology page for the formula and how each value was derived.

Further reading

• Stocking ideas by tank size