Neon Tetra

The neon tetra is a small freshwater characin in the family Characidae, native to clear and blackwater tributaries of the upper Amazon basin in Peru, Colombia, and Brazil. First described in the 1930s, it quickly became one of the most widely kept aquarium fish in the world due to its brilliant, structurally produced coloration and peaceful shoaling behavior. It is closely related to the similar-looking cardinal tetra, with which it is frequently confused. Wild populations remain common in South America, and most fish sold in the aquarium trade today are commercially farm-raised rather than wild-caught.

Neon tetras are identified primarily by their two-tone iridescent stripe pattern.

• Upper stripe: bright iridescent blue-green line from the eye to the base of the adipose fin
• Lower stripe: vivid red-orange band covering roughly the rear half of the body
• Body: small, translucent, torpedo-shaped, 2.5-4 cm
• Fins: small forked tail, no barbels, single small adipose fin near the tail base
• Eyes: relatively large in proportion to the tiny head

Look-alike: the cardinal tetra (Paracheirodon axelrodi) has the red stripe extending along the entire body length rather than only the rear half, and reaches a slightly larger overall size.

Neon tetras live in soft, acidic blackwater and clearwater streams of the upper Amazon basin, typically in densely vegetated, shaded tributaries with heavy leaf litter and slow current. Water in their native range is warm, generally 20-26°C, and often stained tea-brown by tannins from decaying leaves, which reduces light penetration. They occur across parts of Peru, Colombia, and western Brazil, usually in small forest streams rather than the main river channel. In aquariums, they are kept in similarly calm, planted freshwater setups that mimic these dim, soft-water conditions.

Neon tetras are obligate shoaling fish, forming tight groups of six or more individuals as a defense against predation, and they show visible stress and reduced coloration when kept alone. They occupy the middle water column, swimming actively during daylight hours and sheltering among vegetation at night. Their diet is omnivorous, consisting of small aquatic invertebrates, insect larvae, and algae picked from surfaces. Reproduction occurs through egg scattering: adults release adhesive eggs among fine-leaved plants in dim light, with no parental care afterward. Their iridescent stripe is thought to help shoal members maintain visual contact in the dim, tannin-stained water of their native streams, and the species serves as an important prey item for larger fish in its ecosystem.