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What Is the Difference Between Cardinal & Neon Tetras?

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The members of the family Characidae are beloved creatures amid the world of tropical fish pets, and are common fixtures in aquariums. Cardinal tetras (Paracheirodon axelrodi) and neon tetras (Paracheirodon innesi), as near kin, undoubtedly are alike visually, although they are distinctly separate entities -- and different species, for that matter.

Coloration Difference

The upper portions of cardinal tetras' bodies are vivid blue. The lower portions, on the other hand, are an intense crimson color. Neon tetras have extremely close color schemes, with luminous blue upper coloration. The red of their lower bodies, however, is centered around their tails rather than all over their lower halves. Cardinal tetras, in a nutshell, have a little more red on their bodies than do neon tetras.

Size Difference

For the most part, Cardinal and neon tetras grow to similar adult sizes. Cardinal tetras often are just a tad bigger, frequently achieving lengths of 1.5 inches. Neon tetras generally grow to around 1.25 inches.

Water Specifics

Although cardinal and neon tetras flourish in water that is acidic, their necessities are not exactly the same. Cardinal tetras work well with pH levels of between 6.0 and 6.8, while neon tetras succeed with levels of 6.2 to 6.8. Cardinal tetras need water temperatures between 75 and 82 degrees Fahrenheit, while neon tetras have an ever so slightly different range of 76 to 82 degrees. Both varieties of fish are pretty selective about the water in their living environments, however.

Natural Environments

Both types of these fish hail from South America. The Amazon basin is a major hub for cardinal and neon tetras alike. Cardinal tetras in nature tend to spend their lives in tiny and sluggish streams. Free roaming neon tetras often reside in rivers that combine with bigger bodies of water, frequently lakes. The serene fish share a lot of feeding preferences. Cardinal tetras feed on lots of tiny crustaceans, algae, worms and detritus. Neon tetras are big on crustaceans, tiny bugs, plants and worms. In captivity, they readily consume lots of the same foods, too, specifically tubifex worms, daphnia, brine shrimp and flakes.

In captive settings, cardinal and neon tetras both thrive when kept with other members of their species, in units of a minimum of five specimens.


The two species are extremely well-known and appreciated in the realm of tropical fish, but cardinal tetras are thought to have the neon guys beat in that department. More people are believed to have cardinal tetras.