Foods To Avoid Feeding Your Cardinal Tetra

Cardinal tetras are popular freshwater fish that are commonly present in pet stores. Usually, this is because they’re beautiful, relatively easy to care for, and not too expensive. However, there’s one thing that all cardinals need: healthy food. So here we will discuss common foods you should avoid feeding Cardinal tetra.

Some of the toxic and dangerous foods you need to avoid feeding cardinal tetra contain artificial colors and preservatives, high protein foods, and live foods. Foods containing artificial colors and preservatives can be harmful because they can cause liver damage in the fish. High protein foods may be fine for other fish, but cardinal tetras need a more balanced diet lower in protein. Live foods, such as feeder goldfish, can contain deadly parasites to cardinal tetras.

If you avoid these foods, you will give your cardinal tetra a much better chance at leading long and healthy lives.

What Type Of Fish Is Cardinal Tetras?

Cardinal tetras are small freshwater fish that belong to the Characidae family. They originate from South America, Central America, and Trinidad in particular. These fishes are colorful and have a lifespan of about five years.

These fish prefers to live in densely planted areas and the side of the tank where the filter sucks the water, which you should leave open to ensure they can stay safe. Moreover, cardinal tetras are schooling fish, so you should have at least six of them in your tank.

What Foods Does Cardinal Tetra Eat?

Cardinal Tetras are omnivorous and will eat most foods that you give them, but there are some things you should avoid feeding them. They love live food such as brine shrimp, bloodworms, and daphnia, but these can be dangerous if not gut-loaded first. You should also avoid feeding them freeze-dried foods since these often contain artificial colors that can harm the fish.

Cardinal Tetras will do best on small pellets or flakes diet, supplemented with live food once or twice a week. You should never feed them anything more prominent than their eyeballs and crush the pellets if necessary.

What Food Should You Feed Cardinal Tetra?

Cardinal tetras enjoy both animal and plant-based diets. So some of the food that you must feed Cardinal tetras are:

  • Live food: bloodworms, brine shrimp, mosquito larvae, daphnia
  • Frozen food: tubifex worms, plankton, Cyclops, krill
  • Dry food: flake food, freeze-dried bloodworms, tubifex worms, brine shrimp
  • pellets
  • Vegetables: blanched spinach, green peas, cucumber slices
  • Fruit: peeled and deseeded grapes, apple pieces

What Food Should You Avoid Feeding Cardinal Tetra?

Since Cardinal tetras are not picky eaters, they will eat almost anything. Unfortunately, some of the food you feed them may be harmful to their health and can even kill your cardinal tetras.

Here are a few foods that you should avoid feeding Cardinal tetra:


Sugar is not only bad for your oral health, but also it can kill or harm cardinal tetras. A single teaspoon of sugar contains about 16 calories which are empty calories that provide nothing more than energy to the body.

Processed Food

The ingredients found in processed food may be harmful to your fish so avoid feeding them to your cardinal tetras. Processed foods usually have a high salt and sugar content which can be deadly to fish.


While fruit is healthy for humans, it’s not the best food option for fish. Most fruits’ high sugar and acidic content can harm or even kill cardinal tetras. Such fruits are grapes, oranges, lemons, and pineapples.

Raw Vegetables

Like fruit, raw vegetables are not the best food option for cardinal tetras. Some vegetables’ high sugar and acidic content can harm or even kill your fish. Some examples of such vegetables are tomatoes, celery, and lettuce.


The unhealthy ingredients found in chips and crackers can harm your fish. These snacks are high in salt and fat, which can be deadly to cardinal tetras.

What Are The Consequences Of Feeding Cardinal Tetras Unhealthy Food?

Cardinal tetras are susceptible to eating unhealthy food. Usually, they tend to be curious fish who want to investigate anything new or unfamiliar in their environment. Therefore, if you feed your cardinal tetras an array of different foods, then there’s a high chance that some may turn out to be not so good for them.

Some of the problems related to an unhealthy diet in Cardinal tetras are:

  • Poor growth
  • Stunted development
  • Weakened immune system
  • Digestive problems

How To Make Cardinal Tetra Happy And Healthy In Your Aquarium?

If you want your fish to stay fit and healthy, make sure that you choose a suitable tank for them. A 20-gallon aquarium is the best choice if there are not many cardinal tetras in it. It will be good for your fish as well as for their health too.

Besides this, some tips to make your Cardinal tetras healthy and happy are:

  • Do not overfeed them as it can cause health problems.
  • Keep the water clean and change a third of it every week.
  • Make sure that you have a sound filtration system in place.
  • Keep the water temperature between 23 and 26 degrees Celsius.
  • You can also provide them with some hiding places to feel comfortable in their new home.
  • Provide proper lighting, and do not forget to change it every six months.
  • Finally, keep them with non-aggressive fish.
  • Include some leafy greens in their diet to provide them with proper nutrients and minerals to stay fit and healthy.
  • Avoid feeding them food items like peas, lettuce, spinach, tomatoes which contain a lot of water content as it causes bloating to your Cardinal Tetras.
  • Please make sure not to feed your fish any human food as it can harm them.

If you follow these simple steps, your Cardinal tetras will be happy and healthy for a long time.

Some FAQs

What Is The Best Diet For Cardinal Tetras?

The best diet for cardinal tetras is varied, including both live and frozen foods. So while they will eat flake food, it’s also essential to give them other types of food to ensure they’re getting the nutrients they need.

How Much Food Should You Feed Your Cardinal Tetras?

Feed your cardinal tetras as much food as they can eat in a few minutes once or twice per day. If you have more than one fish, make sure to give them enough for each to get its share, so no fights break out over food. Feeding them too little is better than providing them too much – if there’s leftover food, scoop it out and throw it away.

When Should You Feed Your Cardinal Tetras?

Cardinal tetras should be fed in the morning and evening, as per their natural habitat.

Can You Feed Cardinal Tetras Plants?

It’s difficult for cardinal tetra fish to digest plants, so you should not include plants in a regular diet. If you have live plants that your fish enjoy swimming through or around, feel free to feed them those as well.

How To Know Your Cardinal Tetra Is Overfed?

If you overfeed your Cardinal tetra, you’ll be able to tell by looking at its belly. It should look more like a triangle than an oval. If their stomachs are big and round, they’re probably not getting enough food as it is (unless they’re pregnant).

What If One Of My Cardinal Tetras Accidentally Eats A Bad Food?

If one of your cardinal tetras accidentally eats terrible food, they may experience symptoms such as vomiting, listlessness, or changes in color. If you notice any of these symptoms, contact your veterinarian immediately.


In conclusion, it is vital to be aware of the foods that can harm or even kill your cardinal tetras. By following this simple checklist, you can ensure that your fish remain healthy and happy.

Cardinal tetras are an excellent choice for a beginner fish keeper, and with a little bit of extra care, they can be easy to keep healthy and thriving.

If you have any questions or concerns about the foods you are feeding your cardinal tetras, please don’t hesitate to contact us. We’re always happy to help!

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