Tetra fish are among the most popular for aquarists to keep, and for good reason. A cheerful, easy to keep, and energetic little species, the tetra fish comes in a wide variety of colors and types.
And one of the most spectacular of these is the cardinal tetra, which is one of the favorites of aquarium and fish enthusiasts around the world. The cardinal tetra is a vibrant and active little fish, happy to swim in schools among other species and bring bright colors to your tank.
For anyone looking to add a dash of excitement to an aquarium, the cardinal tetra might be the ideal choice for you. But how do you look after cardinal tetras?
Luckily, these exciting fish are very easy to care for and feed, making them a perfect addition to your fish tank, no matter your skill level. Let’s discuss the cardinal tetra a little further below.
Cardinal Tetra: Origin And Appearance
Tetras in general are known for being quite flashy little fish, but the cardinal tetra is one of the most vibrant of its species. With glistening and colorful bodies, a school of cardinal tetra will liven up your entire aquarium, bringing you hours of joy to watch.
Where Do Cardinal Tetras Come From?
Cardinal tetra populations are typically found in the rivers of South America, including the Orinoco and Amazon Rivers. However, some are even found in the freshwater locations of both Central America and Africa.
The tetra is a widespread little fish in their native habitats, where large schools live and propagate peacefully in the wild. When you purchase cardinal tetras, they tend to be shipped to pet stores from native habitats in Brazil and Columbia, collected sustainably through the eco-friendly ornamental fish trade along the Amazon.
What Do Cardinal Tetras Look Like?
The cardinal tetra is a gorgeous little fish with vibrant colors that immediately draw the eye in. They typically come in reds and blues, and are often confused with the neon tetra due to the similarity in markings. However, the cardinal tetra does have a specific color pattern.
Cardinal tetras sport a neon blue band that runs along the side of their body, from their nose to the base of the tail. Underneath this, a red stripe adorns their lower body and extends into a portion of the tail fin. Otherwise, their fins are completely transparent and their underbelly has a lovely cream hue.
The key difference in determining cardinal tetras from neon tetras lies in the length of the red stripe—it extends from the head of the cardinal tetra down to the tail, whereas the neon’s stripe only begins midway down its body.
These colorations are on best display for mature adults when they live in water conditions that have slight acidity and soft water pH levels, bringing out the most vibrancy and healthiest scale growth on the fish.
Interestingly, you can sometimes find cardinal tetras in gold and silver color patterns, but these are much rarer and harder to find at your average pet shop or fish emporium.
How Big Do Cardinal Tetras Get?
In general, cardinal tetras are fairly small aquarium fish, only reaching about 1.25 to 2 inches in length.
However, though they are small, the cardinal tetra does require at least six other tank mates of their same species to be happy, and up to ten or twelve is ideal for a cardinal tetra school. That means plenty of these little fish swimming around and taking up room!
Cardinal Tetra: Lifespan
It is known that tetras tend to live longer in captivity than they do in the wild, and that is no different for the cardinal tetra. These lovely little fish do not have the longest lifespan though, only surviving in a tank for about two to five years.
However, if you keep their tank conditions and diet well balanced and maintained, you will get to enjoy them for as long as possible. Some owners have even reported cardinal tetras that live up to eight years in the right conditions!
Because water parameters are the most common issue that tetra keepers run into, maintaining your water quality will lead to longer lives for your cardinal tetras.
Another way to extend your cardinal tetras’ lifespan is by not pairing them with aggressive fish species in a communal tank. Tetras are notoriously docile, and will not fight back against a fish that wants to hassle—or harm—them.
Cardinal Tetra: Behavior
As mentioned, the cardinal tetra is a placid and gentle fish. They like to swim in schools of other cardinal tetras and spend most of their time in the mid-level of your tank. They get along well with most other species, with a few exceptions, and are very social.
Because of their social requirements, if cardinal tetras are not kept with others, they will become too lonely and isolated, and this could lead to heightened stress levels and even death. They will be more relaxed and healthy when able to interact with other fish—particularly other cardinal tetras.
Cardinal tetras are also notoriously docile, preferring to run away from any danger than face it. And, being rather small, they have no defenses against larger, more aggressive fish. So it’s best to keep your cardinal tetras separated from fish species that are known for being pushy or could snack on smaller tank mates.
Cardinal Tetra: Compatibility
Because cardinal tetras are social little fish, they need to be part of a communal tank, and have a school of cardinal tetras to swim with. In general, the larger the school, the happier your cardinal tetras will be!
Are Cardinal Tetras A Communal Tank Fish?
Cardinal tetras are one of the most social fish when it comes to others of their own species, and have been known to interact pleasantly with other species of fish in a communal tank.
However, they generally like to keep to themselves and will not cause any trouble in the aquarium, which makes them a great addition to your communal tank. Just make sure nothing with big jaws or an aggressive attitude is part of that communal tank as well, or you will find cardinal tetras going missing and being turned into fish snacks!
Best Tank Mates For Cardinal Tetras
Choosing tank mates for your cardinal tetras can be tricky, but if you stick with fish that are smaller than 2 inches when fully grown, your tetras should be safe. There are also a few larger fish that work well in conjunction with cardinal tetras.
Some of the best species to pair with cardinal tetras in a communal tank include placid fish such as the following:
- Dwarf Cichlids.
- Dwarf Gouramis.
- Other Tetra Fish.
- Yo-Yo Loaches.
- Zebra Danios.
- Zebra Loaches.
Additionally, you can safely pair small invertebrates with cardinal tetras, as they will not see them as a food source. This includes tank dwellers such as cherry shrimp, mystery snails, and a variety of freshwater crabs.
Cardinal Tetra: Habitat And Tank Requirements
These fish are quite hardy and can withstand a variety of tank setups. However, to keep your cardinal tetras in the best possible health, there are a few specifications that you should maintain your tank and habitat at. You will notice even more vibrant colors in your cardinal tetras’ patterning when the water quality is just right!
Cardinal Tetra Tank Size
These fish may be small, but because of their larger schooling numbers, you do need an appropriate tank to house them. If you have a smaller school and fewer tank mates, a 10-gallon aquarium should be big enough, but for larger numbers, you should use a 20-gallon tank.
Factor about 2 gallons per extra cardinal tetra that you add to the aquarium to account for their schooling and active natures.
Cardinal Tetra Water Requirements
These fish should be kept in a mature tank with soft acidic water that has stable chemistry. Because of these condition requirements, cardinal tetras are not suited for brand new aquariums.
To keep your cardinal tetra healthy and happy, maintain pH levels below 6 and hardness at 4dGH or below. These specific metrics are important to maintain because fluctuations in mineral content will negatively affect their health and shorten the lifespan of cardinal tetras.
Water temperature tends to be less problematic for cardinal tetras, and they can still survive in a tank with slight temperature changes—though for the sake of all fish in the aquarium, these should be kept to a minimum. Keep your water between 73 and 81°F for happy cardinal tetras!
Cardinal Tetra Tank Setup
Though a social bunch, cardinal tetras thrive when they have the option to vanish into aquarium plants or in hides like caves or wood pieces. Make sure to provide plenty of plant life such as Amazon Swords, Anubias Nana, or Java Ferns that grow nice and tall.
Apart from the plants, make sure there is still an open space for your cardinal tetras to swim around and interact with other fish. They don’t typically spend time on the bottom of the tank, so the substrate selection can be either soft or hard.
Lighting is another important aspect of your cardinal tetras’ tank setup, as cardinal tetras prefer a muted light over bright illumination. Keep your tank lit with dim lights, and you can even add floating plants to help moderate the light coverage.
Cardinal Tetra: Diet
Though some keepers find the cardinal tetra diet challenging, as long as you feed your fish regularly and stick to an omnivore selection, you will be successful in maintaining their health.
Feed your cardinal tetras a balanced diet of dried fish pellets, supplemented with plenty of live or frozen foods. The pellets or flakes are ideal for keeping a basic nutritional level for your fish, whereas the live or frozen foods are good for adding extra protein and minerals to the diet.
Use bits of shrimp or other meats, as well as green vegetables, and add them to your cardinal tetras’ tank in small amounts. Feed your fish twice a day on a regular schedule, enough that they can eat it within about two minutes of foraging, but not so much that the food settles on the bottom of the tank and spoils.
Cardinal Tetra: Breeding
You can breed cardinal tetras at home, but it can be difficult to get the process going. But if you begin by replicating their natural breeding environment and providing high-quality conditions for the fish, then you are off to a good start!
Cardinal tetras prefer dim lighting for breeding, so turn down the brightness or switch the aquarium lights off completely. The water conditions should also remain consistent to encourage healthy propagation, so cleaning the tank itself and changing the water once a week is important to avoid algae or pollutants from developing.
Keep your fishes’ diet nutritional and structured as normal, as this will help the female’s body reach a point where she can successfully fertilize eggs. You will know when that is by spotting more rounded bodies on the females where the eggs are.
After a successful courtship, the fertilized eggs should hatch after about three days. The cardinal tetra fry will be too little for the same diet you feed adult tetras, eating infusoria and other small foods instead. You don’t have to worry about separating the young from their parents either, as they will not attack the fry.
Cardinal Tetra: Health And Wellness
The cardinal tetra’s immune system is one of its weaknesses, so keeping the tank and water quality well maintained is important. Change the water regularly to avoid pollutants and algae that could damage your cardinal tetras’ health and delicate digestive system.
The most common disease to keep an eye out for is called Neon Tetra Disease, affecting many types of tetras including the cardinal. It is a parasite that leads to cysts, a loss of color, curved spinature, and other infections, so if you notice any differences in your cardinal tetras, take them to the veterinarian immediately.
But what else lies beneath the surface when we’re talking about cardinal tetras? Let’s explore some other aspects of cardinal tetras in at-home aquariums.
Which Is Better Neon Or Cardinal Tetra?
Both the neon and cardinal varieties of tetras are great options for your fish tank. And though they have very similar specifications as ornamental fish, including vibrancy and ease of care, neon tetras tend to be cheaper to purchase at the pet shop, which is the main difference.
In most other aspects, both neon and cardinal tetras will thrive in similar tank environments and with a varied omnivore diet. So, it tends to come down to availability and price when choosing between the two.
How Many Cardinal Tetras Should Be Kept Together?
Cardinal tetras are very social little fish and require a school of other cardinal tetras in the tank, with at least six in it. However, many fishkeepers choose to have a school of ten cardinal tetras because of their flashy group colors and sociability.
Just make sure that your tank is large enough to accommodate the number of cardinal tetras inside of it—though they are relatively small fish, they do need enough room to move, eat, and explore.
How Big Does A Cardinal Tetra Get?
In the range of aquarium fish sizes, the cardinal tetra is on the smaller end. A cardinal tetra will only grow to be about 2 inches at most, making them only slightly larger than their neon tetra cousin, whom they are often mistaken for. Most cardinal tetras inside a home aquarium only reach about 1.25 inches though.
Are Cardinal Tetras Easy To Keep?
When it comes to maintenance, cardinal tetras are among the easiest fish to keep. They are quite hardy, able to survive fluctuations in water temperatures, have a simple feeding schedule, and do not cause problems with other fish in a communal tank.
However, they do need the right diet and a clean tank, as improper food will lead to issues with their immune system, which can be compounded by bacteria within the habitat if the tank is not properly cared for.
How Often Should Cardinal Tetras Be Fed?
Your cardinal tetras should be fed twice per day, on a scheduled routine. This is generally during the morning and in the evening, but they will become accustomed to whatever times you choose.
Feeding them on time every day is essential to maintaining their good health and keeping them well-nourished, however, tetra fish are hardy and can survive a day without food. But if you will be away for a long period of time, have someone else come in and feed your fish to keep them happy and healthy.
Cardinal tetras are fun, vibrant little fish that can really add color and activity to your fish tank. With schools of six or more, you will have hours of enjoyment, watching them swirl around the plants and objects in your aquarium.
And because of their gentle nature and sociability, cardinal tetras mix well with other types of fish, making them a great addition to a communal tank without bringing significant maintenance needs or feeding restrictions with them.
Hi, my name is Adam and I’m an aquarium enthusiast! I didn’t discover the joys of being an ‘aquarium fanatic’ (as some of my friends call me!) until I was in my 20’s. When I first started out I found it difficult to find all the information I needed so I started this website to compile all the useful information I can think of. Enjoy!