The Colorful Cardinal

The Cardinal Tetra (Paracheirodon axelrodi) is probably one of the most famous members of Characidae otherwise known as tetras. Its one inch long body is comprised of three bold colors: a silver nape from the head to the dorsal fin, a metallic neon blue stripe from the eye to the tail, and a completely red underbelly, as opposed to the Neon Tetra (Paracheirodon innesi) where the red belly only extends from the anal fin back to the caudal fin. The Cardinal Tetra is named after an influential aquarist and fish expert, Herbert Axelrod.

Cardinal Tetras are found in the Rio Orinoco & Rio Negro drainages, through Colombia, Venezuela, and Brazil. Like many other Amazonian species, they prefer soft, tannic water (frequently stained brown with organics) and are found in slow moving parts of streams where they form large shoals in the middle to upper layers of the water column.

Only reaching a size of about one inch, the Cardinal Tetra doesn’t require much space – but it should be kept in large groups if possible. This will allow for their natural behavior, which makes for a better viewing experience and for a less stressed fish! Cardinal Tetra displays should have some flow/water movement, as this will also encourage shoaling behavior. A 20 gallon “long” aquarium would be the bare minimum for a small school, with larger tanks and bigger schools providing more natural behavior. Tank lighting should be subdued, this can be accomplished with hardscape (driftwood, rocks etc) and live plants either tall plants providing shade or plants that float at the surface. Once this requirement has been fulfilled an open area in the center of the tank for the fish to congregate in open water is the last major necessity.

In the wild, these tetras feed on small invertebrates in the water column. In the aquarium they quickly learn to take appropriately sized flakes & pellets, and obviously this applies to aquacultured fish as well. Live & frozen foods will still be appreciated and can help bring fish into breeding condition.

Cardinal Tetras are not the easiest tetras to breed but it can be done. In the wild they will migrate upstream into tiny tributaries to spawn under the cover of very dense vegetation. A breeding tank will have soft, acidic water, and be dimly lit to simulate these conditions. Females tend to be slightly larger, and plumper especially when they are ready to spawn. Like most Amazonian fish, simulating the end of the dry season (lowering water levels, reducing flow, and increasing temperature) with lots of food, followed by large water changes and slightly cooler water can help trigger spawning.

Cardinal Tetras are one of the most iconic fish in the freshwater aquarium hobby and their bright colors warrant the attention they receive. A suitable aquarium with proper water parameters and good food will result in a stunning display of color and behavior. Ask your LFS to get some sustainable cardinal tetras from Aquatropic for you today!