What Type of Fish Are Tetras?

Tetras are tropical freshwater fish, part of the Characidae family in the Characiformes genus. A popular fish for aquarists is the neon tetra, a bright silver fish with delicate-looking fins, a brilliant neon blue vertical stripe running along the center of the body and an iridescent red stripe starting at the center of the body and ending at the caudal fin. While there are a number of fish now commonly sold under the name "tetra," the fish's name origin may actually surprise you.

  1. The Characin Family

    • Fish sold as tetras belong to the scientific order Characin. Characins or Characiformes are small ray-finned fishes that live in shoals, such as the piranha and tetra varieties. Most Characin fish that have "tetra" in their common name were toxonomically listed under the Tetragonopterus genus -- the generic scientific name for a small genus -- when they were originally classified. The taxonomic term Tetragonopterus is a catchall term or "waste basket taxon" that is used to classify organisms that don't fit into any other classification. The Tetragonopterus genus classification is generally given to new species of small fish that need to be phylogenetically studied before they can be properly classified.

    About Tetragonopterus

    • The term Tetragonopterus, defined by Carl H. Eigenmann in 1917, has been used as a generic genus name for fishes lacking distinct or well-defined physical characteristics that set them apart from other fish species. When scientific research proves that a fish species in the Tetragonopterus genus belongs to its own distinct genus, the name is changed. To make fish names even more confusing, some fish sellers added "tetra" to a fish's common name even when the scientific name of the fish was not listed under the Tetragonopterus genus.

    Neon Tetras

    • Paracheirodon innesi, the neon tetra, is one of the most common known tetra species. The brilliant-colored freshwater tropical fish lives in streams found in Brazil, Colombia and Peru. The neon tetra's first scientific name, Hyphessobryoncon innesi, was created by Dr. George S. Myers in 1936. Dr. Jacques Gery created the Paracheirodon genus in 1960 and changed the scientific name of the neon tetra to Paracheirodon innesi. Although neon tetras did not originally have Tetraganopterus in their scientific name, due to their small size, fish sellers sold them under the name neon tetra.

    Other Tetras

    • Tetras are found in rivers and cavern lakes in South America. However, some species of tetras are also found in Africa. The name "tetra" or "tet" has been added to many different species of Characins that are small in size. Examples of these fish are black tetra, lemon tetra, neon tetra, silver tetra and the flame tetra, or the tet from Rio.