Neon tetras reach 4 cm in length, and are considered easy to keep in a community aquarium of at least 50 cm (20 in) long, with a pH of 6.0 to 6.5 and a KH of 1.0 to 2.0. However, they will die if traumatized by dramatic changes to their environments. They tend to be timid and, because of their small size, should not be kept with large or aggressive fish which may bully or simply eat them. Fish that mix well in an aquarium are guppies, other types of tetras, such as the rummy-nose tetra, cardinal tetra, and glowlight tetra, and other community fish that live well in an ideal tetra water condition. Mid-level feeders, they are best kept in schools of six or more, for the shoaling effect when they move around the tank. They shoal naturally in the wild and are thus more brightly colored and more active when kept as a shoal as opposed to singly. The color and the iridescent stripe of this fish may become dim at night, and can be virtually invisible after a period of darkness. The color may also fade during a period of stress, such as human intervention into the tank. Neons are best kept in a densely planted tank with subdued light and an ideal temperature of 21–27 °C (70–81 °F) to resemble their native Amazon environments.
Neon tetras are omnivores and will accept most flake foods, if sufficiently small, but should also have some small foods such as brine shrimp, daphnia, freeze-dried bloodworms, tubifex, which can be stuck to the side of the aquarium, and micropellet food to supplement their diets. A tropical sinking pellet is ideal, as most brands of these include natural color enhancers that bring out the color in neon tetras. Some frozen foods, including frozen blood worms, add variety to their diets.