Body is 2 inches (5 cm) in length. Usually females are a little larger and have larger stomachs than males. The body is elongated, laterally compressed, and has an adipose fin. The body's coloration consists of a broad, iridescent, blue-green, longitudinal band that extends from the tip of the snout, through the eye, to the caudal peduncle. Below this, there is a bright red band which extends to the base of the tail. The fins are colorless, and the back is brownish-red.

The Characins form one of the largest families of fishes in the world.  Cardinal Tetras do the best when kept in subdued light where under such conditions spawning may taking place, often at night or at any rate in subdued light.  In 24 to 30 hours the eggs hatch, and in three or four days the fry are free-swimming. They are usually found in small rivers and pools in the Amazon, the basin of Negro river, which are soft water based.

Most have teeth and an adipose fin.  Some only have teeth only in the upper jaw.  Although they have teeth they are very peaceful, seldom fight, and are not picky eaters.  They like to swim in schools.
 

In the production of eggs among the plants, Cardinal Tetras pay no attention to them. This tetra is easily mistaken with its close cousin, the Neon tetra (Paracheirodon innesi).

One of the most gorgeous of the aquarium fishes.  It has full red colored lower body extending from  below the eyes to the tail.  Compared to the Neon tetra, the Neon tetra only has half of its lower body in red. 

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