Breeding the Cardinal Tetra requires very soft water in the 1-2 dH range, a pH of 5-6, and low lighting levels. The female may lay as many as 130 eggs and the adults should be removed at this time. The eggs will hatch in about 24 hours and will become waterborne in approximately five days.
The Cardinal Tetra Paracheirodon axelrodi is a spectacular fish and one of the most popular aquarium fish of all time. It is very charming in appearance and behavior. This serene yet gregarious fish needs to be kept in a school. A group of these flashing tetras will make a brilliant display in any aquarium.
The Cardinal Tetra has a distinctive color pattern with a brilliant neon blue center line above a bright red. It is known as the “big brother” of the Neon Tetra, which it closely resembles in color pattern. However, the Cardinal Tetra's red coloration extends the whole length of its body, while on the Neon, the red is limited to its back half. To add a bit of variety, breeders have also developed a “gold” strain of Cardinal Tetra that is available from time to time.
The Cardinal Tetra is also slightly more delicate than the Neon Tetra. But like the Neon, it will only be comfortable in a school. Buy the best stock available, preferably from a local breeder as opposed to a mass producer. Also, choose its tankmates carefully. The Cardinal Tetra is the natural prey of many fish, including even many other tetras.
With optimal water conditions and a well-thought-out tank, the Cardinal Tetra's colors will become even more vibrant. Keep its water soft and acidic. Plant the tank heavily, providing some hiding places and a lot of swimming space. Dark substrate and bogwood will make this fish's coloring appear even brighter. Avoid harsh lighting because it will not help the Cardinal Tetra's coloration and because this fish doesn't like it.
If kept in good conditions, the Cardinal Tetra is easy to maintain and resistant to disease. However, in an unstable tank, it will die off very quickly. The worst fear of a tetra keeper is the Neon Tetra disease, an essentially incurable and highly contagious disease of unknown origin and cause. It was first diagnosed in Neons, where it earned its name, but it can actually affect many other species.