Neon Tetra

Paracheirodon innesi comes from the clear and blackwater streams of the upper Amazon basin in Peru, Colombia and Brazil. Its signature is an iridescent blue stripe with a red band on the rear half — colours that intensify when the fish is calm and among its own kind, and fade under stress or poor water.

Tank & water. Neons are small, reaching about 3–4 cm (1.5 in), but they are active and need swimming room: a 57 litre (15 US gallon) tank or larger suits a proper school. They evolved in soft, acidic water and prefer pH 6.0–7.0 and temperatures of 21–27 °C (70–81 °F). Because they are captive-bred in vast numbers, quality varies, and newly imported fish can be delicate — a fully cycled, stable tank matters.

Temperament. They are peaceful shoaling fish and should be kept in groups of at least six, ideally more; a lone neon or a pair will be stressed and pale. They mix well with other small, calm community fish and shrimp, but can be eaten by larger fish and should not share a tank with anything big enough to swallow them.

Diet & care. Neons are omnivores that accept quality flake and micro-pellets alongside small frozen foods such as daphnia and brine shrimp; feed small amounts they can finish quickly. Avoid confusing them with the similar cardinal tetra, whose red stripe runs the full length of the body while the neon's covers only the rear half. A densely planted tank with subdued light and a dark substrate shows their colour best and mimics the tannin-stained streams they come from. Because they are sensitive to nitrite and to abrupt changes, they should be added only to a fully matured, stable tank rather than a freshly cycled one, and acclimatised slowly to avoid shock.