Neon Tetra

Quick facts

Overview

The neon tetra (Paracheirodon innesi) is the fish that shimmers — a tiny characin with a neon-blue line and a red flash, dazzling when a real school moves together. It is inexpensive, peaceful, and one of the most recognisable fish in the hobby.

It has a reputation as both "easy" and "delicate", and both are true depending on timing. A settled neon in mature, stable water is hardy and long-lived. A neon dropped into a brand-new, still-cycling tank — the classic beginner mistake — often does not make it. Decades of mass-breeding have also softened the ornamental strain, so buying healthy stock helps.

Water & tank

Neons want soft, slightly acidic-to-neutral water (pH 4.0–7.5, 1–12 dGH) and — importantly — they like it cooler than most community tropicals, at 21–25 °C / 70–77 °F. Keeping them too warm shortens their lives; this is one of the most common quiet mistakes.

The single biggest factor is tank maturity. Neons are sensitive to the ammonia and nitrite of an un-cycled or unstable tank, so add them only to a fully cycled, settled aquarium — never as the first fish in a new setup. Give a shoal at least ~40 L / 10 US gal (SeriouslyFish recommends a 60 × 30 cm base), planted, with gentle filtration.

Feeding

A micro-predator by nature — feed a good small-grade flake or micro-pellet as the base, plus tiny live or frozen foods (daphnia, baby brine shrimp, cyclops) for colour and condition. Their mouths are tiny, so keep food small.

Feed small amounts once or twice a day, only what the school clears quickly.

Behaviour & tankmates

A model peaceful community fish that must be kept in a group — a lone or trio neon is stressed and pale, while a school of 6+ (ideally more) colours up and behaves naturally.

Keep with other small, peaceful species (rasboras, small tetras, corydoras, dwarf shrimp). Avoid fin-nippers and, crucially, anything big enough to eat them — a neon is a bite-sized snack for angelfish and other larger cichlids.

What to expect

A new group may look pale and dart for cover at first; in a calm, mature, planted tank they settle within days and start schooling in the open.

Bright, unbroken blue-and-red colour and tight schooling are your daily "all is well" signs; persistent fading or a fish separating from the group is worth a closer look.

Myths, kindly busted

When to act

We triage, not diagnose — but these are worth a closer look (starting with a water test):

• A new neon looking pale, hollow-bellied, or hiding — check the tank is fully cycled and test ammonia/nitrite/nitrate first.
• A bent spine, a fading or broken blue line, and lumps can indicate "neon tetra disease" (untreatable and contagious) — isolate an affected fish and do not add new stock until resolved.
• White spots, clamped fins, or rapid breathing across the group point to water quality or ich — test the water and act early.

Sources & further reading

• SeriouslyFish — Paracheirodon innesi — Adult ~30 mm SL; recommended 60 × 30 cm base; temperature 21–25 °C / 70–77 °F (cooler); pH 4.0–7.5; hardness 1–12 dGH (soft); peaceful shoaling community fish; ornamental strain vigour reduced by commercial breeding.

Written & fact-checked by The Finfern Team against the sources above — kind, general guidance, not a diagnosis. If something looks wrong, test your water and, if it persists, contact a fish-savvy vet.

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