Cardinal Tetra is arguably one of the most popular aquarium fish.
The Cardinal Tetra will have the red stripe the full length of its body on the lower half, whereas the Neon Tetra will have the red stripe only half way. These tetras make excellent community tank mates and for best results you should keep them in a school (shoal) of 6 or more.
Originating from South America, this species is found in the Orinoco and Rio Negro tributaries all the way to western Colombia. Other locations have also reported schools of cardinals, likely comprised of fish that have escaped from collectors. Manaus, in northern Brazil, is one such location where clusters of cardinals have made themselves at home.
The rainforests that cover their waterways are usually very dense and let very little light through. Cardinal tetras favor these shaded areas with slow-moving or standing waters that are very clear. They live in large schools, and it is not unusual to find them in groups numbering into the hundreds. Their native habitat generally has extremely soft, acidic water, often with a pH of 5. They live in shoals, mainly in the middle water layers, where they feed on worms and small crustaceans.