The Neon Tetra (Paracheirodon innesi) is another very popular freshwater aquarium fish, closely related to the Cardinal Tetra — and often confused with it. Iridescent blue stripe across the body (like the Cardinal Tetra). Red stripe starts midway down the body and extends to the tail (unlike the full-length red stripe on the Cardinal Tetra). Slightly smaller and slimmer than the Cardinal Tetra. Grows to about 1.5 inches (4 cm) — a bit smaller than the Cardinal Tetra.