The “Tetras” are mostly tropical South American fish, and certainly the most popular aquarium species are all from that part of the world, although by far the majority of the stocks available to the hobby are from domestically bred fish, mainly being bred on the opposite side of the world to South America! Although not all are peaceful species, the majority are, and grace tropical aquariums all over the world.
The Cardinal Tetra (paracheirodon axelrodi) is a living jewel. The tiny body has a red lower area of the flank, topped by a brilliant lateral line, like a beam of laser light set above red velvet. That bright line can be green or blue.
The Black Neon Tetra (hyphessobrycon herbertaxelrodi) makes a superb contrast fish to run with other tetras. The sooty black flanks and green fluorescent lateral line combine beautifully to make a very attractive fish.