What Is the Difference Between Cardinal and Neon Tetras?

The cardinal tetra and neon tetra share many superficial similarities, but they are very different fish. The cardinal tetra, or Paracheirodon axelrodi, grows slightly larger in size but is more susceptible to adverse aquarium conditions than neon tetras, or Paracheirodon innesi. They also exhibit subtle differences in appearance, and significant differences in behavior within the aquarium environment.

  1. Red Coloration

    • A neon tetra's body is mostly clear or lightly silver-colored, with the trademark neon blue strip running from its head to tail, and the red coloration manifesting predominantly in its rear body and tail. Cardinal tetras have a similar blue streak and a clear or silver-colored dorsal section. Their red markings differ from neon tetras in that they are not confined to the rear of the body; instead, the cardinal tetra's entire ventral section is red.

    Hardiness

    • Cardinal tetras are delicate and have a lower survival rate in aquarium environments where nitrate, nitrite or ammonia levels become high. Neon tetras, which are much hardier, can survive the initial cycling of a new tank, as well as the elevated pollutant levels associated with infrequent or improper tank maintenance. Because of their higher resistance to substandard water quality, neon tetras are better-suited to aquariums kept by inexperienced hobbyists.

    Ideal Habitat

    • Cardinal tetras thrive in temperatures from 73.5 to 80.5 degrees Fahrenheit, and water with a pH level of 4.0 to 6.0. They reach sizes of up to 2 inches, making them more able to fend off aggression from other fish than the smaller neon tetras. Neons prefer soft water with a pH of 6.8 to 7.0 and a temperature of 72 to 78 degrees. Neon tetras also fair better under subdued lighting and prefer floating plants, which they use as both food and cover from larger predators.

    Captive Breeding

    • Neon tetras adapt well to captivity and can often be coaxed into breeding. Cardinal tetras require live food and fine-leaved plants to breed, while neon tetras breed when offered nearly any regular food source and proper water quality. Because of this difference in breeding habits, cardinal tetras are more frequently caught in the wild and shipped to dealers within the pet trade, while captive-bred neon tetras are common and easy to acquire.