The cardinal tetra or Paracheirodon axelrodi is native to the Amazon River. Cardinals are among some of the most colorful freshwater fish varieties available commercially. They are a member of the family Characidae more commonly known as Characids. Black skirts are also commonly referred to as black tetras or black widow tetras. 

Cardinal tetras and neon tetras  look very similar in appearance. There are, however, subtle differences in body markings that can be used to distinguish them from one another. Cardinals have a red stripe or band that extends from their head to the base of their tails. Neon tetras have the same band but it starts mid-body and runs back to the tail rather than extending the entire length of the body. The cardinal tetras color palette tends to be a little more vibrant than that of neon tetras. Adult cardinals are a little larger than neons.

Cardinals reach approximately 2 inches in length. Even though they are a smaller variety of fish, cardinals need ample room to swim. They are not well suited for cramped living conditions. They are mid-tank swimmers and prefer a longer rather than taller swimming environment. This makes them the perfect candidate for wall mounted aquarium lines.

Cardinal tetras are docile in nature. They function well in a community environment devoid of more aggressive species. They are a shoaling fish. The addition of several to your fish tank will help them mimic their behavior in their natural habitat. Cardinals do not thrive as a solitary fish. Under ideal conditions you can expect your cardinals to have a five year life span.

Like all natives to the Amazon River, the cardinal tetra thrives best in soft, slightly acidic water. A 6.8 pH level is premium. Aquarium stores sale water conditioners specifically for Amazon fish species. The cardinal functions best in water temperatures ranging from 70-79°F.

They are omnivores. There is no need to worry about specialty fish food products when raising tetras. Any freshwater tropical fish flakes will work.

It is difficult to distinguish males from females. They are identical in color. The female’s body tends to be a little rounder when they are carrying eggs.

Unlike bleeding heart tetras, cardinals will reproduce in captivity. They are most likely to breed at night or in a dimly lit tank. Cardinal tetras are egg layers. They scatter their eggs. Like all tetras, cardinals will eat their eggs. A good way to prevent this from happening is to add a layer of marbles to the bottom of your fish tank. The eggs will slip through to the bottom where they will be safe until hatching time.


Here are some handy tips to follow if you intend to spawn tetras. Keep them in a separate breeding tank provided with floating plants. They won’t breed in hard, alkaline water. You can filter the water through peat or add thin layer to your substrate to imitate perfect mating conditions. Make sure the peat contains no chemical additives.

After spawning remove the adult fish from the breeding tank. Cardinal tetra fry hatch in about 24 hours. Once they hatch, they can be fed liquid fry food, infusoria, or rotifers. Both are readily available at fish specialty stores. Larger fry will thrive on small amounts of hard-boiled egg yolk ran through a food processor. Powdered eggs will also work.