The neon tetra has a light-blue back over a silver-white abdomen. The fish is characterized by an iridescent blue horizontal stripe along each side of the fish from its nose to the base of the adipose fin, and an iridescent red stripe that begins at the middle of the body and extends posteriorly to the base of the caudal fin. The fish is partially transparent (including fins) except for these markings. Sexual dimorphism is slight, with the female having a slightly larger belly, and a bent iridescent stripe rather than the male's straight stripe. During the night, the blue and red become gray or black as the fish rests. It reactivates once it becomes active in the morning. It grows to approximately 4 cm (1.5 in) in overall length. They have recently become available in a long-fin variety.
In the wild they inhabit very soft, acidic waters (pH 4.0 to 4.8) Ideal pH for aquarium is 7.0, but a range of 6.0 to 8.0 is tolerable. They can have a lifespan of as long as ten years, or normally two to three years in aquarium.
Neon tetras are considered easy to keep in an aquarium of at least 10 gallons. Their ideal parameters are the following
Temperature: 72°-76°F (22°-24°C) Nitrate: <20 ppm pH: 6.0 to 7.0 GH: <10 dGH KH: 1-2 dKH
They are shoaling fish and must be kept in groups of at least 6 but will be more active in groups of 8-12 or more.
Neon tetras are best kept in a densely planted tank to resemble their native Amazon environments.