Why Is One Cardinal Tetra Taking All the Food?

If you have ever had a large community tank, you know that it can be challenging to keep everyone fed. Many people have questions about why there is one cardinal tetra in their tank that appears to be taking all the food.

There are many reasons why one Cardinal tetra might be taking all the food. They are poor diet, lack of nutrition, unhealthy living conditions, stress, aggressive companion, or overstocking.

Besides this, a new cardinal tetra owner might have many questions regarding them. So, to answer all your concern about this issue. We will look at some factors contributing to why your tetras might be fighting for food.

Is Cardinal Tetra Picky Eater?

Some people may wonder if cardinal tetra is a picky eater, and the answer to that is no. They will pretty much eat anything you put in their tank – however, there could be instances where one might take all the food for themselves.

Usually, Cardinal tetras are omnivorous fish. However, in the wild, cardinal tetras eat both vegetative matters and small animals such as insects and crustaceans that fall into the water from trees or other land-based vegetation. They will also feed on algae growing in their habitat at times when food is scarce to supplement their diet with enough nutrients so they can survive.

Can Cardinal Tetra Eat More Than Its Need?

Yes, the cardinal tetra may consume most of the food. It can be due to several factors, such as hunger or territoriality. When there is a limited amount of food available, the cardinal tetra may become more aggressive in defending its resources. As a result, this could lead to other fish becoming malnourished.

Why Is One Cardinal Tetra Taking All The Food?

One cardinal tetra is taking all the food, leaving other fish hungry. It might seem like an unfair situation, but it’s pretty natural for a dominant fish to take more than its share. The predominant fish may even eat smaller fish! So why does this happen?

Some of the reasons for this behavior are:

Poor Water Condition

If the water quality is poor, it can lead to fish becoming stressed. It can make them more aggressive and cause them to dominate the tank.

Limited Resources

When there are fewer resources, such as food, a dominant fish will often take more than its share to survive.


Cardinal tetra may be taking more food than usual because of stress. It could mean that other fish are aggressive, or the tank is not as comfortable as they would like.


Cardinal tetras are very sensitive to the chemical scents in the water. If another fish is releasing too much of a smell (such as stressed-out chemicals), it might make this cardinal tetra feel threatened and more likely to take all the food for itself. A common cause of excess scent is overfeeding, so make sure only to feed your fish what they can eat in a few minutes.


The dominant cardinal tetra is taking more food because it’s trying to assert its dominance over the other fish. This behavior you can usually see in larger fish or those in the tank for a while and know that they’re in charge.

Aggressive Companion

If one of your cardinal tetras has an aggressive companion, it will likely become stressed. As a result, it may become more aggressive and take all the food for itself to survive.

Lack Of Proper Nutrition

Not all fish have a good diet. A cardinal tetra that isn’t getting the right amount of food might be an example of this. Also, if you’re new to keeping fish in your aquarium, you may not know how much or what kind of food your fish should eat.

Inadequate Space

Fish will naturally establish a dominant hierarchy in an aquarium. The bigger, more aggressive fish will usually take the most food and space. If you have a small tank or too many fish, it can be more challenging for weaker fish to get enough to eat.

Sudden Change In Environment

If you just changed how many fish are in your tank or rearranged the décor, it could make them feel like they’re not safe anymore. It can cause them to become stressed and even more aggressive than usual. The dominant fish will usually take more food to defend themselves if this happens.

How To Manage This Behavior Of Cardinal Tetra?

If you notice one Cardinal tetra is taking all the food, you can separate it.

Take away other fish that are not the same type of cardinal tetras and give them more food to have enough for themselves.

With this behavior of one Cardinal Tetra, it might be able to let your other fish know that it should leave some food for everyone else as well.

If this still does not work, you might want to try and get another Cardinal Tetra to keep the first one company.

This way, it will have someone to eat with and will not feel the need to take all of the food for itself.

You can also try rearranging your tank to spread out more. So the Cardinal Tetra will not feel as though it needs to take all of the food.


What To Feed Cardinal Tetra?

Cardinal Tetras are omnivorous and will eat most foods. They enjoy flake food, freeze-dried bloodworms, tubifex worms, brine shrimp, and daphnia. You can also give them small amounts of vegetable matter, like blanched spinach or boiled peas.

How Much To Feed Cardinal Tetra?

The cardinal tetra can usually be fed twice per day. Determining the amount of food to give them each time is essential. It helps to ensure they are getting all of their nutritional needs met and not overfed, which could cause harm.

For this, leave the food for a few minutes. If the cardinal tetra has not eaten all, remove the leftovers. The cardinal tetra should eat all the food within two minutes.

What Is The Most Common Commercial Food For Cardinal Tetra?

The Tetra brand is the most common commercial food for cardinal tetras. It comes in various sizes and forms, including flakes, sticks, pellets, and granules. You can also make your homemade fish foods to control what goes into them.


If you’re not sure what’s causing your cardinal tetra to be so aggressive, it might help to do a quick check of the tank. Make sure that there are no leaks or cracks in the lid and filter. Check all the plants for snails, as these can cause damage, releasing extra chemicals into the water. As always, make sure to keep the tank clean and change the water regularly. If you can’t seem to resolve the issue, it might be time to re-home that dominant cardinal tetra!

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