Many people get the cardinal tetra confused with its more well-known cousin, the neon tetra. While both have a blue horizontal stripe, the cardinal tetra’s red stripe spans the full length of its body, whereas the neon tetra’s red stripe only covers the back half. This peaceful, 2-inch (5 cm) fish gets a little bigger than the neon tetra, so put a school of at least 6–10 in a 20-gallon tank or larger. They can be a little shy if you have a smaller group, so increase their numbers and consider adding a lot of live aquarium plants as cover. Even when the aquarium light is off, you will catch a glimpse of their glowing blue dashes weaving in and out between the leaves. For more details, read the full article.