What Food Do Cardinal Tetras Eat? A Guide to Fish Nutrition

Cardinal tetras are one of the most popular species in the aquarium hobby. They’re beautiful, peaceful fish that can live for decades, and they’re relatively easy to care for, only requiring a few weekly water changes and some regular food delivery. But what food do Cardinal tetras eat is always a constant question amount beginners.

Like most other tropical freshwater aquarium fish, Cardinal tetras eat a varied diet consisting primarily of different kinds of flake and frozen foods such as brine shrimp, bloodworms, or daphnia. They will also readily accept live food, including white worms ( nematodes ) and blackworms ( tubifex ). Further, being omnivorous, Cardinal tetras also enjoys some plant-based foods like blanched cucumber slices and algae wafers.

The following article will go over some of the most popular choices for feeding Cardinal tetras.

What Is Cardinal Tetras?

Cardinal tetras, scientifically referred to as Paracheirodon axelrodi, are freshwater fish belonging to the genus Paracheirodon in the family Characidae. They have been a popular choice of tropical community tank owners for many years. They get their common name from their vibrant red bodies that genuinely make them stand out against any aquarium background.

Cardinal tetras are small fish that can grow up to an inch in length, though they usually remain smaller than this. For reference, the average size cardinal tetra is roughly one-fourth of an inch long at adulthood. They have silver bodies with iridescent blue lines running from their gills to their tails and beautiful red coloration on their fins and bodies.

Some owners mistake Cardinal tetras with another species of fish, the neon tetra (Paracheirodon innesi). But if you are attentive enough, you can easily distinguish neon tetras by a black spot at the base of their caudal fin instead of red like the cardinal tetras.

What Is The Natural Habitat For Cardinal Tetras?

Cardinal tetras originate from the Amazon River, primarily in Brazil. They can live in the Amazon and Essequibo basins, as well as on Marajo Island. Cardinal tetras prefer a tropical climate with high humidity and temperatures between 22°C to 27°C (72°F-80°F). The water should be a slightly acidic pH between six and seven.

Cardinal tetras are present in blackwater rivers, which are dark due to the tannins leached by decaying leaves. Like other fish from this region, cardinal tetras need warm water with very little oxygen content. Cardinal tetras also live in rivers with high water flow and murky waters.

Usually, these fish swims in a slow-moving current. However, they can adapt to an extensive range of water conditions. They also require lots of covers to hide and rest. Therefore, Cardinal tetras need a lot of plants in the aquarium for resting, breeding, and as a food source. It would be best if you never kept Cardinal tetras with other slow-moving fish such as bettas, gouramis, angelfish, or catfish that prefer slower waters.

What Food Does Cardinal Tetras Eat?

Cardinal tetras have a varied diet, including small crustaceans, worms, insect larvae, snails, and zooplankton. They will also eat algae if it is available to them. In addition, Cardinal tetras need a varied diet of brine shrimp, bloodworms, tubifex worms, and daphnia. Cardinal tetras will eat live or freeze-dried versions of these food items.

A diverse variety is the best way to ensure that your Cardinal Tetra receives all necessary vitamins and minerals from their fish food. But there are some Cardinal Tetra foods that you should feed sparingly or avoid altogether.

Cardinal tetras will eat live blackworms and mosquito larvae. But it is not good to feed them earthworms because they are difficult for Cardinal Tetras to digest.

What Are The Plants Based Food Cardinal Tetras Eat?

Cardinal tetras are omnivorous fish, so they eat both plants and meat. However, since cardinal tetras eat more plant-based foods than meat, their diet should consist of around 50 percent vegetables, with the other half comprises protein foods.

Vegetables that you can feed to your Cardinal Tetra include:

  • Sliced cucumber
  • Zucchini
  • Iceberg lettuce
  • Peas
  • Blanched Spinach
  • Blanched Kale

Feeding your Cardinal Tetra a varied diet of these vegetables is important, as it will provide them with fiber and nutrients. You can feed them once or twice per day in small quantities to ensure that they overeat.

Be careful when feeding vegetables to Cardinal Tetras because they are prone to swim bladder issues. Vegetables high in calcium can lead to swim bladder problems for Cardinal tetra fish that have this condition. So, you should avoid feeding them too much spinach, kale, or peas.

What Are The Food That Cardinal Tetras Use As Protein Source?

Cardinal tetras need protein for the development of their muscles and other body parts. Cardinal tetras eat a variety of life, frozen and pelletized fish foods as a protein source. These include:

  • Bloodworms
  • Frozen brine shrimp
  • Brine shrimp (crushed)
  • Daphnia
  • Frozen bloodworms
  • Frozen krill or other crustaceans
  • Live blackworms (bloodworm larva)

Cardinal tetra fish have a high metabolism rate and will eat more food than other types of tropical fish. So, it would be best if you fed Cardinal tetras at least twice per day. However, you may even increase their feeding schedules in warmer water conditions or during breeding.

What Are The Nutritional Requirements For Cardinal Tetras?

Cardinal Tetras should not eat food that is high in fat and sugar content. Cardinal tetras also prefer their fish food to be low in protein but contain the right amount of vitamin C and E.


A Cardinal Tetra only needs 0.05% protein per day (source here), so there isn’t a need to feed Cardinal Tetras food high in protein. However, too much of a good thing can be harmful, so don’t give your Cardinal Tetra too much fish food with lots of protein content.


Cardinal Tetras can eat food with fat.  But be cautious that you do not offer them too much of it. Too much fat is unhealthy for Cardinal tetras and will assist in producing excessive wastes. Along with this, excessive fat intake can also induce several diseases. So, it is best to give Cardinal tetras fat in limited portions.


It is best to avoid giving your Cardinal Tetra foods that contain sugar (source here). While they can eat some sugars like glucose, Cardinal Tetras will not need to eat high in sugar food.

Vitamin C

Cardinal Tetras require vitamin C and E. Foods with a low amount of these vitamins won’t be necessary for you to provide your Cardinal tetra. However, foods with the correct vitamin C and E will be best for your Cardinal Tetra. Cardinal Tetras can eat high vitamin C and E content, but there is no need to provide them with too much of these vitamins.

Vitamin D

Cardinal tetras do not require foods containing Vitamin D. You don’t have to worry about providing Cardinal Tetras with high vitamin D content since they don’t need it. Cardinal tetra will eat low in Vitamin D but won’t want to consume foods containing too much of this vitamin.


Foods for Cardinal Tetras should be low in calcium. It’s not necessary to provide Cardinal Tetras with food that has a high calcium content (source here). Cardinal tetra will eat some foods containing calcium, but there is no need to offer them too much of these.


Cardinal Tetras only require 0.03% phosphorus per day (source here). So most aquarists suggest avoiding feeding Cardinal Tetras food that is high in phosphorus. But, conversely, you should not offer Cardinal tetra fish food with too much of this nutrient since there isn’t a need for it, and you don’t want their overeating.

What Are The Food Cardinal Tetras Should Not Eat?

Some of the foods are very harmful to Cardinal tetras. So, it is better not to give those foods to them. But, on the other hand, Cardinal tetras love live food, and they will eat almost anything. So, it might seem like a good idea to feed your Cardinal tetras some of these foods. But you’ll regret doing that when the fish become sick or die from eating something harmful.

Some of the food that you should never feed Cardinal tetras are:

  • Raw meat from beef, pork, or poultry
  • Egg whites
  • White bread
  • Seeds from fruits such as apples, oranges, and bananas

Cardinal tetras should never eat these because they contain a lot of sugar, making your fish sick or even killing it.

Some FAQs

How Often Should Cardinal Tetras Eat Their Food?

Cardinal Tetras are an omnivorous fish species that eat both plants and animals in the wild. As a result, they should be fed food containing plant matter and meaty foods like brine shrimp or bloodworms every day to ensure proper nutrition. Cardinal tetras can also eat algae wafers if there is not enough other food.

How Many Days Can Cardinal Tetra Go Without Food?

Cardinal Tetras will go without food for up to three days if they are in a single species aquarium. After that, these fish will eat the scraps and leftovers of other fish to survive for a more extended period.

In most cases, they also eat the live plants and the smaller animals or their eggs. However, when there is a lack of sufficient food, Cardinal tetras become voracious and eats anything and everything.

How Much Food Should Cardinal Tetra Eat?

Cardinal Tetras should continuously be fed as much food as they can eat in two minutes every day. Cardinal Tetra fish cannot survive without proper nutrition and care, so it is important to feed Cardinal Tetra fish with a high-quality flake or pellet food that contains both plant matter and meaty foods like brine shrimp or bloodworms.

If you house Cardinal tetras with other fish, you should feed them less than usual to ensure they eat all of their food. Cardinal tetra can also eat algae wafers if no proper nutrition is available.


Summing up, Cardinal tetras need a variety of foods. They have specific dietary needs, but you feed them properly, Cardinal tetras can live for several years. These fish should eat a good mix of pellets and veggies to get all the nutrients they need.

If you can give Cardinal Tetras the proper nutrition, they can live for several years. Cardinal tetras eat food high in protein, like bloodworms or brine shrimp, and enjoy a variety of plant life.

Hopefully, we have answered the question of What Food Do Cardinal Tetras Eat?. Cardinal tetras are easy to take care of but need a good diet to live long, healthy lives!

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