How Big Do Tetras Get?

Tetras are a group of freshwater aquarium fishes belonging to the family Characidae. Dozens of tetra species are available in the aquarium trade, but certain species are more popular than others. Neon tetras, black skirt tetras and cardinal tetras, for example, are some of the most popular species because they are well-suited to the general community tank. When selecting tetras for the community tank, consider the adult size of the fish to avoid overcrowding. Because different species of tetra grow to different maximum sizes, research the individual species before making a purchase.

  1. Maximizing Tetra Growth

    • The average adult size of tetras varies according to the individual species, but most species achieve a maximum length between 3/4 inch and 5 inches. Maintaining high water quality in the tank and providing a healthy diet are two of the most important factors in whether tetras will reach their maximum size. If the water quality in the tank is poor, tetras may become stressed or fall ill and will not grow properly. Similarly, a diet that does not provide all the nutrients tetras need will prevent these fish from reaching their maximum adult size. To ensure proper growth of tetras, perform regular water changes to keep water quality in the tank high and offer a varied diet of live, frozen and flake foods.

    Small Tetras

    • Many of the smaller species of tetra which do not grow larger than 2 inches are well-suited to the general community tank. Lemon tetras, ruby tetras, black phantom tetras and glowlight tetras are a few of the species which reach a maximum length of 2 inches or less. Neon tetras, serpae tetras and cardinal tetras also reach a maximum size between 1.5 and 2 inches. Because these tetras are so small, they should not be kept with large, aggressive species like cichlids, which may view them as prey. When kept with other peaceful species, however, these fish are likely to thrive in the community setup.

    Medium Tetras

    • Though the majority of tetra species fall within the 3/4- to 2-inch size range, a few species of tetras reach a maximum size between 2 and 3 inches. Black widow tetras, also called black skirt tetras, are a popular choice for beginning aquarium hobbyists and they typically grow up to 2.5 inches. The bleeding heart tetra, another popular species, grows to a similar size. Buenos Aires and Congo tetras reach a maximum length around 3 inches, and both Colombian and redeye tetras grow to about 2.75 inches. Tetras of this size can still be kept in the community tank and can often be kept with larger, more robust species such as angelfish and other cichlids.

    Large Tetras

    • Most species of tetra reach a maximum size under 3 inches, but several large species of tetra do exist. The long-finned tetra, for example, grows up to 5 inches long and makes a great addition to the large community tank. In the wild, bucktooth tetras can grow as large as 6 inches, but most aquarium specimens grow no larger than 4 inches. The largest tetra is the payara, or vampire tetra, which is a predatory species that can grow up to 4 feet long in the wild. Though this species belongs to the family Cynodontidae, it belongs to the same order as other tetras and is frequently referred to as a type of tetra or characin.