FaunaHub

Tetra

FishFreshwaterAquarium

A neon tetra (Paracheirodon innesi) with a bright blue-and-red stripe.

Neon tetra (Paracheirodon innesi).

Image: Holger Krisp, CC BY 3.0, via Wikimedia Commons.

Overview

"Tetra" is a common name for many small freshwater fish in the characin group, especially popular aquarium species such as the neon tetra and cardinal tetra. This page is a group-level overview; the neon tetra (Paracheirodon innesi) is used as a familiar reference. Tetras are prized in the hobby for their small size, bright colours, and tight schooling behaviour, but they are social fish with specific needs.

Habitat & Range

Many popular tetras come from the warm fresh waters of tropical South America, including the Amazon basin, where species such as the neon tetra live in soft, often tannin-stained streams. Other tetras occur in Africa and Central America. In aquariums they are tropical fish needing heated, filtered water. Habitat and water preferences vary by species, so a description of one tetra does not apply to all.

Diet

Tetras are generally omnivores that feed on tiny invertebrates, zooplankton, and plant matter in the wild, and on prepared foods in aquariums. This page does not give feeding quantities; appropriate diet and amounts depend on the species and tank and should follow qualified aquarium guidance.

Behavior

Most aquarium tetras are shoaling fish that feel secure and behave naturally in groups; keeping them in adequate numbers is widely considered important for their welfare. They are usually peaceful and active, making them common community-tank fish, though some species can nip fins. Behaviour depends on the species, group size, and tank conditions.

Human Interaction & Conservation

Tetras are among the most popular freshwater aquarium fish and are bred in large numbers for the hobby. They are aquarium animals, not wildlife; releasing them is harmful. Some wild tetra populations can be affected by habitat change and collection pressures. Conservation status varies by species and should be checked against current sources. Responsible keeping means an appropriate school size, maintained water, and qualified help if fish appear unwell.

Appearance & Recognition

Tetras are typically small, slender fish, often with bright or iridescent markings. The neon tetra is a classic example, with a shimmering blue-green stripe along the body and a red stripe to the rear. Many tetras have a small adipose fin between the dorsal fin and tail, a feature of the characin group. Colours and patterns vary widely across the many species.

Similar Animals

Tetras are characins, related to other characin fish and, more distantly, to the carp-family fish covered on FaunaHub. In community aquariums they are often kept alongside peaceful species; angelfish, however, are larger cichlids that may view the smallest tetras as prey, so combinations need care.

Freshwater aquarium basics →Aquarium care hub →

More photos of the tetra

A neon tetra swimming among aquarium plants.

A neon tetra, a small schooling characin.

Image: Wojciech J. Płuciennik, CC BY-SA 4.0, via Wikimedia Commons.

Frequently Asked Questions — Tetra

How many tetras should be kept together?
Tetras are schooling fish and are widely recommended to be kept in groups rather than alone or in pairs, because grouping supports natural behaviour and reduces stress. The right number depends on the species and tank, so follow qualified aquarium guidance.
Are neon tetras and cardinal tetras the same?
No. They look similar — both have a blue and red stripe — but they are different species and differ in the extent of the red stripe and in some care details. "Tetra" as a whole covers many species, which is why this page is a group-level overview.
Are tetras good community fish?
Many tetras are peaceful and popular in community aquariums, but some can nip fins and the smallest species can be eaten by larger tank mates. Compatibility depends on the species and setup, so research each combination carefully.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.