Cardinal tetra facts for kids
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The cardinal tetra (Paracheirodon axelrodi) is a small, colorful freshwater fish. It belongs to the Characidae family. These fish come from the upper Orinoco and Negro Rivers in South America.
Cardinal tetras grow to about 3 centimeters (1.2 inches) long. They have a bright, shiny blue line across their body. Below this line, their body is a vivid red. This red color reminds people of a cardinal's robes, which is how they got their name.
Many people confuse cardinal tetras with neon tetras. They look similar, but cardinal tetras have more red color. The red on a neon tetra only goes halfway to its nose. Also, the neon tetra's blue stripe is not as bright.
Cardinal tetras are very popular aquarium fish. For a long time, it was hard to breed them in tanks. Now, many breeders are successful. You can often tell if a fish was caught in the wild or bred. Wild-caught fish sometimes have damaged fins.
Some fish experts believe we should support the fishing of cardinals in the Amazon. Thousands of people in the area earn money by catching these fish. If they stopped, they might start cutting down trees instead. This would harm the environment.
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About the Cardinal Tetra
American fish expert Leonard Peter Schultz first described the cardinal tetra in 1956. He named it Cheirodon axelrodi. The name "axelrodi" honors another fish expert, Herbert R. Axelrod.
The common name, cardinal tetra, comes from its bright red color. People sometimes also call it the red neon tetra.
Cardinal tetras can have different colors. Some forms from the Rio Negro area have less blue in their stripe. They might look "gold" or "silver-blonde." The usual form from the Rio Negro has a blue stripe that goes all the way to its back fin. Fish from the Orinoco area have a stripe that stops shorter. This difference might mean they are a different type of cardinal tetra.
What They Look Like
The cardinal tetra has bright red underparts. It also has a shiny blue line that runs along its side. This blue color is special. It comes from tiny crystals in their skin. These crystals reflect light.
The color you see depends on how you look at the fish. If you look from below, the blue might look deeper, like sapphire. If you look from above, it might look more greenish. Cardinal tetras seem to grow bigger when kept in aquariums than in the wild. They have a large stomach and a small gut.
Where They Live
Cardinal tetras are found in South America. They live in the upper parts of the Orinoco River. This river flows through Colombia and Venezuela. They also live in the upper Rio Negro River in Brazil.
How They Live
What They Eat
Cardinal tetras look for food in slow, shallow water. They mostly eat small animals. They find these animals on plants, roots, and fallen leaves underwater.
They often eat tiny insect larvae, like those of midges. They also eat small crustaceans, such as water fleas and copepods. Sometimes, they eat other insect eggs, tiny worms, and amoebas.
Reproduction and Life Cycle
In the wild, cardinal tetras swim upstream in large groups. They go to parts of the river that are covered by the rainforest canopy. These areas are very shady, with almost no sunlight. Here, many fish gather to lay their eggs.
When fish are ready to spawn, the male chases the female into fine-leaved plants. The female will look fuller if she has eggs inside her. If she is ready, she lets the male swim next to her. Together, they release their eggs and sperm.
Lifespan
In nature, cardinal tetras might only live for about one year. But in aquariums, they can live for several years. If you want to breed them, you should try to copy their natural home.
A study in Brazil looked at cardinal tetras in bad water conditions. The fish died if the water was too cold (below 19.6°C or 67.3°F). They also died if it was too hot (above 33.7°C or 92.7°F). Very low pH (below 2.9) or very high pH (above 8.8) also killed them.
Cardinal Tetras in the Aquarium Trade
There is a whole industry in Barcelos, Brazil, where people catch fish for aquariums. This town is on the banks of the Rio Negro. The local people value catching cardinal tetras. They act as guardians of the environment.
Because they can earn a living from fishing, they are less likely to harm the environment. For example, they might not cut down trees. From 2006 to 2015, over 92 million cardinal tetras were sent out from the Amazonas state. This was more than 64% of all ornamental fish exports from that state.
Keeping Them in Aquariums
It's important to keep cardinal tetras in groups. You should have at least 6 fish, but more is even better. Keeping them in larger groups makes them feel safe and comfortable. It also helps them show their natural schooling behaviors. This reduces stress and makes their colors look even brighter.
The smallest tank size recommended is usually 10 US gallons. However, many fishkeepers suggest 20-gallon tanks are better. Longer tanks are often better than tall ones. This is because they offer more surface area.
Cardinal tetras will eat many types of food. They like flake foods and pellets made for small fish. They also eat different kinds of vegetables. The best water pH for them is around 7.5, but they can also do well at 8.0 pH. The water temperature should be kept between 75°F (24°C) and 80°F (27°C). This helps prevent sickness and stress.
You need to be careful when choosing other fish for their tank. Avoid any fish that are too big or too active. They might eat or bother the small tetras. Cardinal tetras get along well with other small tetras and Honey gouramis. They are also peaceful with freshwater shrimp, like Cherry Shrimp.
See also
- List of freshwater aquarium fish species
- Project Piaba
