Do Cardinal Tetras Need A Filter? Do You Know Why??

Cardinal tetras are easy to care for, and they make good beginner fish because of their hardiness. Unfortunately, most fish keepers forget to ask whether or not they require an aquarium filter, as most other species do. Do cardinal tetras need a filter?

Yes, Cardinal tetras do need a filter. A filter is necessary for almost all fish. They help maintain water cleaner by removing waste particles before it breaks down into ammonia which is toxic to the fish and can kill them if the levels get too high.

In this blog post, we will be discussing Filter and Cardinal tetra. Hopefully, this post will be informative enough to clear all your doubts regarding Cardinal tetra.

Introduction To Filter

The filter is a device for cleaning the water to make it free from harmful chemicals. It removes particles, dirt that builds up in your tank over time and helps keep the environment clean, leading to healthier fish. It also helps to keep the tank healthy by removing waste and other substances.

Filter does not work alone. It requires some pump for water movement via an impeller or something similar. Nevertheless, a filter is beneficial, and certain fish species get along with filters like Cardinal Tetras.

Do Cardinal Tetras Need A Filter?

Yes, Cardinal Tetras do need a filter. However, the filter is part of the Cardinal tetra biology if you want them to keep in your aquarium. Without it, you will not receive excellent results for this fish.

The common Cardinal tetra is a small freshwater fish present in the rivers of the Orinoco River to the Rio Negro tributary of the Amazon River in South America. They are popular aquarium fish, and beginner aquarists often keep them because they are easygoing.

You can identify Cardinal tetras by their red stripe running from the gills to the tail fin. However, as with all tropical fish, you need to research and take steps before putting them in your tank. Filter, water quality, and temperature are all things you need to consider before purchasing Cardinal Tetras for your aquarium.

Why Do Cardinal Tetras Need Filter?

Cardinal tetras are excellent swimmers and need a solid filter to keep the water clean. Filter systems generate currents that help circulate oxygen within the tank and remove waste particles from the aquarium environment.

Moreover, some of the reasons why cardinal tetras need filters are:

Filter Increases Oxygen Through Aeration

The filter increases oxygen through aeration by forcing water into tiny spaces inside the filter, allowing more room for air. This process also keeps your tank crystal clear as well as increases cardinal tetra’s comfort.

Filter Promotes Healthier Cardinal Tetras

Cardinal tetras are very sensitive to their environment. Filter helps cardinal tetra feel more comfortable by providing clean, clear water free of waste particles and toxins that can harm or make them sick.

Filter Also Prevents Bacteria Growth

A dirty tank with bacteria growing in it will most likely contaminate the water in your tank. So, the filter prevents bacteria growth by reducing biological loading.

It is a massive plus for cardinal tetras because they are sensitive to such an environment.

Filter Provides Safe Habitat for Cardinal Tetras

The filter provides a safe habitat as it keeps the water crystal clear and prevents over-population. Furthermore, this environment is beneficial to cardinal tetra’s healthy growth and development.

The filter also provides a home for cardinal tetra’s eggs and makes them feel safe, which is another plus if you plan to breed cardinal tetras.

Filter Keeps Water Clean & Healthy

The filter keeps the water clean and helps you create a healthier aquarium environment by removing waste particles from the tank. The filter takes water from the aquarium and pushes it through filter media such as sponges, carbon filters, or gravel.

Is It True That Cardinal Tetras Do Not Need A Filter?

In most cases, the answer to this question is no. At the same time, it may be true that some people have been able to keep aquariums with fish like Cardinals and Bettas for years without using filters or heaters. But still, there are lesser chances of fish surviving long enough without a filter.

A filter is a necessity for almost all aquariums because it will keep the tank clean and healthy. Cardinal Tetras need this type of environment if they are going to thrive.

In addition to keeping your fish safe from toxins in the water, filters also help with water circulation. It makes sure that oxygen can get into the water as well as removing wastes.

Cardinal Tetras are very active swimmers. Therefore, they need regularly circulated water around the tank to provide enough oxygen and keep their skin healthy.

What Type Of Filter Do Cardinal Tetras Need?

Cardinal Tetras are one of the most popular freshwater fish that people keep as pets. They come from South America and prefer to live in calm waters with little water flow or current. Still, they do require a filter because Cardinal Tetras are very sensitive to organic waste.

Some of the filters that are best for Cardinal Tetras are:

Under Gravel Filter

The under gravel filter is an excellent way to save space without sacrificing filtration. These can be as simple as an airstone, powerhead, and small amount of substrate that runs into your main tank, or you may choose to create something more elaborate.

These are the most inexpensive filters for aquariums because gravity pulls the water down into a gravel bed. The filters remove the water through various types of media for filtration.

Under gravel, filters use up large amounts of space. In addition, they typically do not provide high levels of biological filtration, so you should use them in conjunction with other methods such as power filters or canister filters. These are best for tanks that are 20 gallons or less.

Canister Filter

Canisters are one of the most effective and efficient ways to filter aquarium water. They use a combination of mechanical filtration via sponges or chemi pellets and biological filtration through many different media types. But neither limited to ceramic noodles, bio balls, bio max rings, or bio-wheels.

Canisters are best for tanks that need high water quality and require relatively little maintenance due to the large volume of filtration mediums included with most canisters. However, they do come at a higher cost than other types of filters.

Sponge Filter

Sponge filters are the simplest and most effective means of adding biological filtration to your aquarium. They use an air pump or powerhead to push water into a sponge that breaks down back, which helps remove ammonia, nitrites, and nitrates from the tank’s water.

Sponge filters work best for tanks up to 25 gallons but can work for larger tanks as well.

Air-driven sponge filters are the most basic sponges and require more maintenance because air pumps need regular cleaning. In contrast, water pump-driven ones do not risk becoming clogged with organics over time, leading to increased ammonia levels in your tank’s water.

Internal Filter

Internal filters are another form of biological filtration, although, unlike sponge filters, You can also use them for mechanical purposes. These filters use an impeller to pull water through various media or sponges inside the unit itself. The beneficial bacteria filter the water before releasing back into your tank’s water, thus providing both physical and biological filtration.

Internal filters are best or tank 15 gallons or more extensive and require less maintenance than other types of filters. However, it is important to regularly clean the impeller to prevent buildup, which leads to decreased water flow through your filter media, resulting in increased ammonia levels.

Trickle Filter

Trickle filters are an efficient means of water filtration that combines biological and physical media. These types of filters work by pumping water from your tank’s filter into the trickle filter itself, where various bacteria break down the water before releasing back into the aquarium, thus providing mechanical, chemical, and biological filtration.

Trickle filters are best for tanks up to 50 gallons, although You can use them in larger tanks as well.

Hang On Back Filter

Hang-on-back filters are among the most popular types in freshwater aquariums because they provide both mechanical and biological filtration in a convenient package that hangs off the side or top of your tank. They use an impeller to draw water into various media inside the filter box before releasing it back into your tank, thus providing physical, chemical, and biological filtration.

Hang-on back filters are best for tanks up to 30 gallons, although you can also use them in larger aquariums. They require little maintenance apart from cleaning the impeller regularly, which should only take a few minutes every other week.

Power Filter

A power filter is another type of filtration that provides physical and biological filtration via an impeller that draws water through various media inside the unit.

Power filters are best for tanks up to 20 gallons, although you can use them in larger aquariums as well. They require little maintenance apart from cleaning the impeller regularly, which should only take a few minutes every other week. So depending on how often you clean your tank out entirely by siphoning the gravel.

Hobbyists with multiple tanks may opt to use two different types of filter media in one power filter instead of using a separate unit for each aquarium to save space and money. However, they will likely need to purchase a higher-end model to do so.

Wet/Dry Filter

The wet/dry filter is the most effective and efficient mechanical filtration used in a marine aquarium. The design allows media to place inside the chamber, where it becomes submerged underwater (wet).

As waste builds up on top of this media bed, by gravity, fresh incoming seawater will flow over and through it, becoming filtered. When the chamber is full, water will drain from a bottom spout back into the aquarium to refilter and aerate before returning to your tank.

Wet/dry filters are highly efficient because they allow you to place large amounts of filtration media in one location.

What Are The Things To Consider When You Buy Filter For Cardinal Tetras?

Cardinal tetras are a prevalent fish that is usually present in small groups of six or more. They are not picky at all when it comes to their environment. They will generally do very well even if you have poor water quality, as long as there’s plant cover. These little guys need medium-to-high water flow as well as a filter.

Some of the things to consider when you choose a filter for Cardinal tetras are:

Filter Media

It is important to choose a filter that has easily replaceable media so you can change it as needed without having to buy an entirely new filter. You’ll need activated carbon and biological filtration for sure, but many other kinds of media might be good options, too: Bio balls, Carbon, Chemi-pure elite, Phos-zorb, etc.

Number Of Filters Per Tank Size

Cardinal tetras are a schooling fish, so you’ll need to have at least six in your tank, but the bigger, the better. Generally speaking, for every ten gallons of water, you will want one filter. So if you plan on keeping 20 gallons of water, get two filters.

Filter Size Per Filter Number

An essential thing to consider is how large the filter needs based on its flow and gallons per hour (gph) rating. You want a filter that has enough power for your tank size but is not so powerful that it will damage your fish or plants with too much water flow.

The Filter Power

The measuring unit for filter power is gallons per hour (gph). As a general rule of thumb, you don’t want it to be more than half the size of your tank. So if you have a 20-gallon tank, you should try to choose a filter that has at least a maximum flow rate of 100 gallons per hour.

How To Rate Filter Power?

There are two main ways to rate the filter power: the maximum flow rate or the actual size of the filter in gallons. In addition, you can measure the filter power by how many aquariums it can fill up to its total capacity within 24 hours.

So, if you have a 20-gallon tank and choose a filter with a maximum flow rate of 100 gallons per hour, it will fill up your tank in just over six hours.

Filter Maintenance In Cardinal Tetras Tank

Buying a filter itself will not be helpful for the health of Cardinal Tetras. You must know how to maintain the filter. Thus, you and your fish will get the full benefit of the filter. Some tips for the maintenance of filter in Cardinal tetras tank are:

Clean the Filter

The first thing you should do is clean your filter. Please do not use soap or bleach for this purpose, as soaps may harm the fish and their habitat. Instead, take a brush, soak it in cold water and scrub away all dirt from it using small circular motions, then rinse with fresh water thoroughly to remove traces of soap or bleach.

Change Filter Cartridges

After cleaning the filter, you need to change its cartridge. It is not a good idea to leave empty cartridges inside your Cardinal tetras’ tank. Harmful bacteria might grow through them, which may damage fish and their habitat.

For this purpose, check the owner’s manual for how many cartridges can fit into your filter. You should change the number of filters in a week if you have more than one cartridge inside it.

Replace Filter Media

When changing media, check whether you need to reuse or dispose of them. Some types of Cardinal tetras tanks need only disposable ones that you can throw away after use, while others require reusable media you need to rinse and reuse.

The filter cartridge is the most important part of the tank because it contains all bacteria colonies that perform filtering, so you should change them at least once a month to maintain a healthy fish environment.

The Filter Must Not Create Any Noise.

Cardinal Tetras are very sensitive to noise, so the filter should not create sound while running in their tank. However, you must make sure that the filter is working well and doesn’t make noise because otherwise, you will disturb your Cardinal tetras, and they won’t get the best environment for living.

If you don’t want to use a Cardinal tetras tank or have some problems with maintaining it, there are several alternatives for this purpose, such as using an air pump and airstone, which is less costly than filters. However, it works the same way.


Cardinal tetras are very active fish, so having an internal filter would not be ideal for them. Filter recommendations will vary depending on the size of your tank and what type of filtration you have or want to incorporate into your aquarium setup.

So, an external filter is best for cardinal tetras because they are small fish that need clean water conditions in their tanks. If you go with an internal filter, it should be for 20 gallons or less.

Thank you for reading. For more information, please feel free to contact us.

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