How to Breed Cardinal Tetras

Cardinal tetras are small, exuberant fish that are often kept in home aquariums because of their bright coloration. These little fish, which grow to between about 1 and 2 inches, are colored in electric red and blue stripes. This makes them a showy addition to the aquarium. Cardinal tetras closely resemble the more common neon tetra. However, unlike many other tetra types, cardinal tetras are very sensitive to water conditions. This sensitivity can make both keeping them and breeding them a challenge.

Things You'll Need

  • Freshwater breeding aquarium
  • Fine leafed aquarium plants
  • Thermometer
  • Water testing kit
  • Water pH additives
  • Live fish foods
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Instructions

    • 1

      Set up a freshwater breeding aquarium, which will solely house the cardinal tetras as they prepare to spawn. This separate aquarium will ensure that no other fish pose a threat to the eggs or young cardinal tetras after they hatch. This aquarium needs to be at least five gallons in size, although larger aquariums often make breeding easier, as it's easier to stabilize water conditions in a larger space.

    • 2

      Place several fine-leafed freshwater aquarium plants around the bottom of the breeding aquarium. These plants are where the cardinal tetras will scatter their eggs.

    • 3

      Install a thermometer in the breeding aquarium, and closely monitor the temperature of the water. Abrupt changes in water temperature can cause a failure in breeding. Cardinal tetras generally prefer a water temperature between 73 and 81 degrees Fahrenheit. For breeding, some cardinal tetras prefer a higher temperature, close to 80 degrees, while other fish may feel more comfortable with a temperature at the lower end of the spectrum. If your breeding attempts don't work, try carefully adjusting the water temperature with an aquarium heating or cooling system.

    • 4

      Use a water testing kit to carefully monitor the pH level of the water in the breeding aquarium. Like temperature, a stable pH level plays an important role in spawning with cardinal tetras. The pH level should remain between 5.0 and 6.0. Use water additives to raise or lower the pH level.

    • 5

      Place a school of cardinal tetras in the aquarium. A school is about five or six fish, although you can add more if your aquarium is large enough. Cardinal tetras feel safest when they are in a school and are therefore more likely to breed. It's also difficult to determine a cardinal tetra's gender. By placing a school in the breeding aquarium, you are more likely to have at least one male and one female fish.

    • 6

      Feed the cardinal tetras a diet of live foods, such as bloodworms. This rich diet will encourage spawning.

    • 7

      Wait for the cardinal tetras to breed. When water conditions are stable and live food has been fed for several days, a male and female will spawn. The female will release about 500 eggs into the aquarium plants. These eggs will hatch within about a day.

    • 8

      Remove the adult fish from the aquarium after spawning. Adult cardinal tetras will eat their young.