Information on Cardinal Tetras

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Cardinal tetras are peaceful tropical freshwater fish that are easy to keep in aquariums. Named for the long, red stripes that extends the length of their bodies, these little fish are favored for adding color to their fish tank homes. In aquariums that resemble their natural habitat, they will thrive.


Cardinal tetras, paracheirodon axelrodi, originate from the South American countries of Brazil, Venezuela and Columbia. They are found in areas with ample tree covering where water from the Upper Orinoco and Negro rivers accumulate. If you are purchasing your cardinal tetras from a pet store, chances are your pets will have been bred and raised in captivity in conditions mimicking their natural habitat.

Physical Characteristics

People often confuse cardinal tetras with the popular neon tetras because the two fish look similar. Both are long and slender. However, cardinal tetras are larger and have more red coloration on their bodies. While neons have short red stripes, cardinal tetras have red stripes that runs from their heads to their tail fins. Above the red stripe, cardinal tetras have silver and blue coloration. These hardy little fish typically grow to about 2 inches (5cm) in length.

Life in Captivity

Cardinal tetras are easy fish to keep as pets. They do not require a lot of tank space and can be kept with other small, passive fish. Though they typically live about a year in their natural environment, these active fish can live up to five years in captivity provided they do not have to share their tanks with aggressive tank mates. Cardinal tetras are also easy to feed, because they thrive on a variety of tropical fish flakes and pellets. However, if you want a water-dwelling pet that will reproduce, you may be disappointed with this species. Cardinal tetras are notorious for their lack of breeding in captivity.


If you want a very passive community fish, you will enjoy the brightly colored cardinal tetra. Whether you keep a few of these petite fish or an entire school, you will have a harmonious tank. You can also put your cardinal tetras with other peaceful community fish provided they are not predatory in nature.


Your cardinal tetras will enjoy an aquarium that is similar to their natural habitat. By covering the bottom of your tank with aquarium sand and adding driftwood, you will create an ideal environment for your fish. Adding live plants will help increase the acidity level of the water, which is similar to the South American waters that become acidic from the fallen leaves of trees. You can also add colorful aquarium-approved decorations that help highlight these attractive little fish.


In the warm waters of South America, cardinal tetras are used to soft water with balanced acidity and alkaline. If you keep the water in your pets' tank at a pH of 4.6 to 6.2, your little friends will thrive. Since they originate from tropical climates, cardinal tetras need warm water that ranges from 73 to 81 degrees Fahrenheit (23 to 27 degrees Celsius). These sturdy swimmers also do best in water that is kept clear and clean. Cleaning your tetras' tank by removing and replacing half of the water each week will help to ensure their longevity.

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