Cardinal Tetra Identification Guide
Recognize a cardinal tetra by its iridescent blue stripe paired with a red band that runs the full length of the body.
Read the full Cardinal Tetra encyclopedia entry →
Key identification features
- Small, slender, torpedo-shaped body
- Brilliant iridescent blue-green horizontal stripe running from the nose to the base of the tail
- Vivid red stripe running beneath the blue line along the full length of the body, from head to tail
- Mostly transparent belly and lower body, allowing internal organs to be faintly visible
- Small adipose fin between the dorsal fin and tail
- Small size, typically 3-5 cm
Common look-alikes
- Neon tetra: the red stripe covers only the rear half of the body rather than running the full length, and the fish is slightly smaller overall
- Green neon tetra: the red coloring is reduced to a very short patch near the tail, with the blue stripe dominating most of the body
- False neon tetra: a duller, less vivid blue stripe and a red band that is faint or largely absent
Where you'll see one
Cardinal tetras are native to blackwater and clearwater tributaries of the Amazon and Orinoco river basins in South America, schooling in soft, acidic, tannin-stained water shaded by overhanging forest.
Frequently asked questions
How do I tell a cardinal tetra from a neon tetra?
Check how far the red stripe extends: a cardinal tetra's red band runs the entire length of the body, while a neon tetra's red is limited to the rear half.
How do I tell a cardinal tetra from a green neon tetra?
A cardinal tetra shows a full-length red stripe alongside the blue line, while a green neon tetra shows only a short patch of red near the tail.