Cardinal Tetras: Care Guide and Tank Requirements

Cardinal tetras are stunning freshwater fish that can add a vibrant touch to any aquarium. These fish are popular among aquarists for their bright coloration and relatively easy care. As an avid fish keeper, I have had the pleasure of keeping cardinal tetras in my aquarium and have found them to be a joy to watch.

Native to South America, cardinal tetras are found in the Amazon River basin in countries such as Brazil, Colombia, and Venezuela. In the wild, these fish live in schools and prefer soft, acidic water conditions. When kept in an aquarium, it is important to replicate their natural habitat to ensure their health and longevity. This includes providing a well-planted tank with plenty of hiding places and keeping the water soft and slightly acidic. In addition, cardinal tetras should be kept in groups of six or more to prevent stress and promote their natural schooling behavior.

Overview of Cardinal Tetras

As an aquarium enthusiast, I have always been fascinated by the beauty of cardinal tetras. These colorful freshwater fish are native to the Rio Negro in South America, specifically Brazil. Cardinal tetras belong to the Characidae family and are scientifically known as Paracheirodon axelrodi.


Cardinal tetras are small and typically grow up to 1.5 inches in length. They have a unique and striking appearance, with a fluorescent blue stripe that runs laterally throughout their body. This blue stripe is what sets them apart from other tetra species. Their body is also adorned with a vibrant red coloration, which blends into a silver-white color towards the belly.


Cardinal tetras are peaceful and social fish that prefer to live in schools of at least six individuals. They are active swimmers and can be seen darting around the tank, especially in the presence of other fish. Cardinal tetras are relatively easy to care for and are suitable for community tanks as long as water conditions are favorable and other species are peaceful.

Natural Habitat

In their natural habitat, cardinal tetras are found in slow-moving blackwater rivers and streams. The Rio Negro is known for its acidic and soft water conditions, which cardinal tetras prefer. They are also found in areas with a lot of vegetation and submerged tree roots, which provide them with hiding places and shelter.

Overall, cardinal tetras are a great addition to any aquarium due to their colorful appearance and peaceful nature. With proper care, they can live for up to five years, making them a long-term investment for any aquarium enthusiast.

Tank Setup and Water Parameters

Tank Size

When setting up a tank for cardinal tetras, it is important to consider the size of the tank. A 20-gallon tank is ideal for a small group of six cardinal tetras. If adding more than six, increase the size of the tank by an extra two gallons per fish.

Water Parameters

To keep cardinal tetras healthy, it is important to maintain specific water parameters. The ideal water temperature for cardinal tetras is between 73°F to 81°F, with above 75°F being preferred. The pH level should be between 5.0 to 7.5, with below 6.0 being ideal. Water hardness should be between 2 to 6 KH, and the water needs to be slightly acidic and very soft. Too many dissolved minerals in the water could be detrimental to the fish’s health.


A filter is essential for keeping the tank clean and maintaining good water quality. A hang-on-back filter or a canister filter is recommended for a cardinal tetra tank. The filter should have a flow rate of 5 to 10 times the volume of the tank per hour.


Cardinal tetras prefer a dark substrate, such as sand or gravel. The substrate should be fine-grained and not sharp, as sharp substrate can injure the fish. A depth of 2 to 3 inches of substrate is recommended.


Cardinal tetras do not require intense lighting, but it is important to provide a natural day/night cycle. A timer can be used to regulate the lighting and provide a consistent schedule.


Cardinal tetras prefer a heavily planted tank, with plenty of hiding places and areas to swim. Driftwood and rocks can be added to the tank to provide hiding places and create a natural environment. However, it is important to avoid sharp decorations that can injure the fish.

Overall, setting up a tank for cardinal tetras requires attention to detail and specific water parameters. However, with proper setup and maintenance, cardinal tetras can thrive in a community aquarium and provide a beautiful display of color and movement in a tropical setting.

Cardinal Tetra Care

As an aquarium enthusiast, I have found cardinal tetras to be a fascinating addition to any tank. Proper care of these beautiful fish is essential for their health and longevity. Here are some important aspects of cardinal tetra care:


As an omnivore, the cardinal tetra requires a varied diet. Providing a mix of live and frozen foods such as bloodworms, brine shrimp, and daphnia, along with high-quality flakes or pellets, will ensure that the fish receive the necessary nutrients. It is important to avoid overfeeding, as this can lead to health problems.


Cardinal tetras are social fish and thrive in groups of at least six. They are also compatible with many other peaceful fish species, including catfish and neon tetras. However, it is important to avoid aggressive tankmates, as cardinal tetras are relatively small and can become stressed in such situations.


Cardinal tetras are sensitive to changes in water conditions and can become stressed easily. Maintaining a stable environment with consistent water parameters and avoiding sudden changes in temperature or pH level is crucial for their well-being.


When selecting tankmates for cardinal tetras, it is important to consider the compatibility of the species. Peaceful fish that share similar water requirements and temperament are ideal. Avoid aggressive or territorial species, as these can cause stress and harm to the cardinal tetras.


Cardinal tetras are relatively hardy and can adapt to a range of water conditions. However, they prefer acidic water with a pH level between 6.0 and 7.0. Providing a well-maintained aquarium with appropriate lighting and filtration will help to keep the fish healthy and thriving.

In conclusion, caring for cardinal tetras requires attention to their diet, tankmates, stress levels, compatibility, and water parameters. With proper care, these beautiful fish can provide years of enjoyment and beauty in any aquarium.

Breeding Cardinal Tetras

Breeding Cardinal Tetras can be a challenging task, but it is possible with the right conditions and care. In this section, I will cover the breeding process, eggs, and fry of Cardinal Tetras.


To breed Cardinal Tetras, you will need a breeding tank with stable water chemistry. The tank should have a pH of 5.0 to 6.0 and very soft water of 3 to 5 dGH or below. The breeding tank should have plenty of space for the fish to swim around and a separate egg-laying device.

The breeding process usually happens in the evening. The male Cardinal Tetra will chase the female around the tank, and when they are ready to mate, they will swim together, releasing eggs and sperm simultaneously.


After the breeding process, the eggs will hatch in about 24 to 36 hours. The eggs are small and transparent, measuring about 0.8 mm in diameter. The number of eggs laid by the female Cardinal Tetra will vary, but it can range from 130 to 500 eggs.

The eggs will stick to the egg-laying device, and they should not be removed from the tank. The eggs will hatch in a few days, and the fry will start to swim freely in about five days.


The fry of Cardinal Tetras are tiny and fragile, and they need special care. They should be fed small amounts of food several times a day, and the water in the breeding tank should be kept clean and well-oxygenated.

The fry will start to develop their coloration at about two weeks old, and they will grow quickly. After about a month, they will be large enough to be moved to a regular aquarium.

In conclusion, breeding Cardinal Tetras can be a challenging but rewarding experience. With the right conditions and care, you can successfully breed these beautiful fish.

Cardinal Tetra Diseases

As a fish enthusiast, I know that keeping Cardinal tetras healthy is crucial. These fish are generally hardy, but they can still be susceptible to diseases. In this section, I will discuss some of the common diseases that can affect Cardinal tetras and how to treat them.


Ich, also known as white spot disease, is a common parasitic infection that affects freshwater fish. Cardinal tetras are no exception. The parasite responsible for ich is called Ichthyophthirius multifiliis. It causes white spots to appear on the fish’s body, fins, and gills. The fish may also become lethargic and lose their appetite.

To treat ich, you can use medications such as malachite green or copper sulfate. You can also raise the temperature of the water to around 86°F (30°C) for a few days. This will speed up the life cycle of the parasite, making it easier to kill with medication. It’s important to note that ich can be prevented by maintaining good water quality and avoiding overcrowding in the tank.

Overall, it’s important to monitor your Cardinal tetras closely for any signs of disease. With proper care and attention, you can help keep your fish healthy and happy.

Buying Cardinal Tetras

As a fish enthusiast, I have always been fascinated by the beauty of cardinal tetras. These small fish with their striking blue and red colors are a great addition to any aquarium. However, before buying cardinal tetras, it is important to consider a few things. In this section, I will discuss where to buy cardinal tetras and the cost associated with them.

Pet Stores

Pet stores are a common place to buy cardinal tetras. However, it is important to choose a reputable store that sells healthy and good-quality fish. Look for stores that have a good reputation and have knowledgeable staff. Ask the staff about the source of their fish and how they take care of them. Also, observe the fish in the store and look for signs of illness or stress.

Another option is to buy cardinal tetras online. There are several online sources that sell healthy and vibrant cardinal tetras. However, it is important to learn as much about the seller and their livestock as possible. Look for reviews and feedback from other customers. Also, check the shipping policies and the condition of the fish upon arrival.


The cost of cardinal tetras varies depending on the source and location. In general, the cost of cardinal tetras ranges from $1 to $5 per fish. However, the price may be higher for larger or rarer species.

It is important to consider the cost of setting up and maintaining an aquarium for cardinal tetras. Cardinal tetras require a minimum tank size of 10 gallons and a heater to maintain a temperature of 73-81°F. They also require a filter and regular water changes to keep the water clean and healthy.

In conclusion, buying cardinal tetras requires careful consideration and research. Choose a reputable pet store or online seller that sells healthy and good-quality fish. Consider the cost of setting up and maintaining an aquarium for cardinal tetras. With proper care, cardinal tetras can thrive and bring beauty to any aquarium.