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10 Great Tank Mates for Cardinal Tetras (With Pictures)

Sarah Psaradelis

By Sarah Psaradelis

Cardinal Tetra

It is without a doubt that the red cardinal tetra is one of the most popular kept shoaling fish in the aquarium hobby. They are small and have vivid colors that look mesmerizing when they reflect light. Their small size allows them to be comfortable in nano tank setups and they are generally a good and peaceful tank mate for many different fish.

Cardinal tetras have blue and red markings with a distinctive silver line cutting through the middle of the two separate color patterns. When they are together in a shoal, their colors stand out in any tank setting.

Although these fish look good by themselves, adding tank mates can make the tank feel a little less empty.

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The 10 Tank Mates for Cardinal Tetras

1. Betta Fish (B. Splendens) – Best for Small Tanks

betta fish
Image Credit: panpilai paipa, Shutterstock
Size: 2–3 inches
Diet: Carnivore
Minimum tank size: 5 gallons
Care Level: Beginner
Temperament: Aggressive

The classic betta fish, whether male or female is a perfect match for red cardinal tetras. Cardinal tetras are good swimmers and can quickly get away from an angry betta fish. Keep in mind you will have to increase the tank size if you want to add a betta to your cardinal tetra tank.

Both bettas and cardinal tetras can be kept in nano environments such as a 10-gallon with one betta and six cardinal tetras. They get along quite well and generally will not bother each other.

2. Guppies (Poecilia reticulata)

Image Credit: Piqsels
Size: 1–2 inches
Diet: Omnivore
Minimum tank size: 10 gallons
Care Level: Beginner
Temperament: Peaceful

Guppies are beautiful colorful fish with long flowing tail fins. They go quite well with cardinal tetras and will rarely interact. You should expect your guppy to hang around the top level of the aquarium or between plants. A group of guppies alongside red cardinal tetras adds stunning color to naturally styled tanks.

3. Corydoras Catfish (C. paleatus)

Corydoras Catfish
Image Credit: Pixabay
Size: 2–5 inches
Diet: Omnivore
Minimum tank size: 20 gallons
Care Level: Beginner
Temperament: Docile

Corydoras are cute and small catfish that spend most of their time cleaning algae off surfaces in the tank. They do not get overly large and should be kept in small groups. They will primarily hang out at the bottom of the tank where they will not interfere with cardinal tetras.

4. African Dwarf Frogs (Hymenochirus)

african dwarf frog swimming
Image Credit: Dan Olsen, Shutterstock
Size: 1–2 inches
Diet: Omnivore
Minimum tank size: 20 gallons
Care Level: Intermediate
Temperament: Peaceful

If you are interested in adding an amphibian friend, look no further than the small African dwarf frog. They are minuscule in size at 1 to 1.3 inches. They are great with smaller shoaling fish like the red cardinal tetra. However, keep in mind that African dwarf frogs prey on slow-moving or vulnerable sick fish. A healthy shoal of cardinal tetras should be able to outswim an African dwarf frog.

5. Kuhli Loaches (P. Khulii)

kuhli loache
Image Credit: slowmotiongli, Shutterstock
Size: 2–5 inches
Diet: Omnivore
Minimum tank size: 20 gallons
Care Level: Intermediate
Temperament: Docile & shy

Khuli loaches are full of personality. They enjoy being in groups of three or more and prefer to hang around the substrate. They require sand so that they can burrow and exhibit their natural behaviors. It is unlikely that cardinal tetras will encounter your Khuli loaches in the aquarium due to Khuli loaches being nocturnal.

During the day, Khuli loaches will huddle under the sand and stick their heads out while being stacked together in a group.

6. Danios (Danio rerio)

giant danios fish
Image Credit: Karel Zahradka, Shutterstock
Size: 1–3 inches
Diet: Carnivore
Minimum tank size: 10 gallons
Care Level: Beginner
Temperament: Playful

Danios are the perfect shoaling fish for cardinal tetras. These colorful fish come in many different colorful man-made colors, or the standard blue and silver color accompanied with stripes. They like to shoal near to the surface and will spend their time skimming the waterline in search of food. Their colors and body shape fit in nicely next to red cardinal tetras.

7. Mollies (P. Sphenops)

gold dust molly
Image Credit: Praveen Aravind, Shutterstock
Size: 3–5 inches
Diet: Omnivore
Minimum tank size: 20 gallons
Care Level: Beginner
Temperament: Boisterous & playful

Mollies are playful and colorful fish that get along with many species of fish, including the red cardinal tetra. They do, however, get significantly larger than most nanofish and should be kept in groups of 6 or more. Mollies swim all over the tank and use their wide mouths to chew off algae. They are a good tank mate if you want a shoaling and algae-eating fish in one.

The same applies to platies and swordtails which fall under the same category as mollies.

8. GMO Widow Tetras (G. ternetzi)

GMO tetra
Image Credit: Pavaphon Supanantananont, Shutterstock
Size: 2–4 inches
Diet: Omnivore
Minimum tank size: 15 gallons
Care Level: Beginner
Temperament: Peaceful

GMO widow tetras are the next best fish in terms of color as a tank mate. They are genetically modified versions of the widow (aka black skirt) tetra. They are referred to as GMOs because they have been colored in a laboratory. They are not injected with dyes, but their color has been bred through the years and is considered man-made. They are a flat and more colorful version of tetras.

The most common colors are yellow, orange, pink, blue, and green. They look striking when kept with red cardinal tetras and are peaceful shoaling fish that need a group of eight or more.

9. Shrimp (Caridea)

Amano Shrimp
Image Credit: Grigorev Mikhail, Shutterstock
Size: 1–3 inches
Diet: Omnivore
Minimum tank size: 10 gallons
Care Level: Intermediate
Temperament: Peaceful & shy

Nearly every type of shrimp can be kept with red cardinal tetras. This can include the neocaridina (red rili, cherry, blue, Sunkist shrimp) or Caridina species like Amano shrimp. However, shrimp should only be kept with cardinal tetras if the conditions allow it. The tank must be heavily planted for this to work out.

10. Pleco (Hypostomus Plecostomus) – Best for Large Tanks

Bristlenose Plecos
Image Credit: TTONN, Shutterstock
Size: 4–15 inches (species dependent)
Diet: Omnivore
Minimum tank size: 30–100 gallons
Care Level: Beginner
Temperament: Peaceful

Some species of plecos get huge! The common pleco can reach an average of 15 inches within the first few years. Whereas some smaller plecos like bristlenose only reach about 5 inches maximum. Plecos get along well with cardinal tetras and do not interact. These peaceful algae eaters work well in a cardinal tetra community tank but keep in mind the tank should be large enough to house everyone comfortably.

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What Makes a Good Tank Mate for Red Cardinal Tetras?

Three stripe Cory (Corydoras trilineatus)
Image credit: Pavaphon Supanantananont, Shutterstock

There are so many compatible tank mates for red cardinal tetras, but it can be difficult to determine what good tank mates are that will cause few to no issues when kept with a shoal of cardinal tetras. Bottom dwellers are a good option for tank mates. This can include fish like plecos or Corydoras.

Albina bristlenose plecos are good if you want to keep a smaller tank with cardinal tetras, whereas a group of Corydoras can fit in a medium-sized tank setup.

Where Do Red Cardinal Tetras Prefer to Live in the Aquarium?

Red cardinal tetras inhabit the middle level of the tank. They rarely go to the top level of the aquarium and will be seen foraging amongst the plants in search of food. They should be kept in groups of six or more to form a proper shoal, but a group of eight is best to avoid any bullying between the shoal.

Water Parameters

The water parameters should be kept within ideal levels. They are sensitive to high levels of ammonia and nitrite but can tolerate up to 20ppm nitrate. The tank should be cycled for 8 weeks before you place them inside their new tank. A filter and weekly water changes are necessary to reduce toxins in the water column.


Red cardinal tetras are small and do not get larger than 1.2 inches. Their small size allows you to easily add a large group in a small tank. Keep in mind that although these are small fish, they still enjoy large tanks so that they can exhibit the same behaviors they do in the wild. A group of eight red cardinal tetras can thrive in a 20-gallon-long tank.

Cardinal tetra
Image Credit: InsectWorld, Shutterstock

Aggressive Behaviors

These fish are not aggressive to other species of fish, but they can get into minor fights amongst each other. Red cardinal tetras display their aggression by chasing other shoal mates. They do not bite or fight till serious injury and all aggressive behaviors are triggered by stress. The main causes are small groups, cramped tanks, and incorrect water temperature.

The 2 Benefits of Having Tank Mates for Red Cardinal Tetras in Your Aquarium

1. Liveliness & Color

Tankmates add more color and liveliness to a red cardinal tetra tank. Guppies and bettas are excellent choices if you aim to add more attractive and unique colors to your tank.

2. Not to Worry About the Space

Nearly all compatible tank mates for this species of fish can be housed in nano tank setups. This means you can enjoy keeping your cardinal tetras even if you have limited space (this excludes plecos and other large fish that grow past 4 inches).

How to Successfully Keep a Community Tank with Red Cardinal Tetras

Cardinal tetra
Image Credit: chonlasub woravichan, Shutterstock

Keeping red cardinal tetras in a community tank is simple and is usually successful. They make great community tank mates and seem to bring in the color and liveliness aspect of quiet community tanks. The tank can contain various compatible fish species that inhabit various levels of the tank.

A good ratio of fish is choosing bottom dwellers, surface shoaling fish, and a pair of larger growing fish as focal points in the tank. Dwarf gourami or mollies make great, medium-sized focal point fish when paired with cardinal tetras in a community tank.

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It is no surprise that red cardinal tetras are a strong attraction to many tank setups. They look appealing amongst heavily planted tanks and get along with many different species of fish. Their small size allows them to be housed in planted nano tanks if they have a filter and heater.

They are readily available from many pet store outlets and are incredibly hardy. They get few diseases and can easily withstand harsh diseases that other fish may be carrying.

We hope this article has helped you to decide on a good tank mate for your shoal of red cardinal tetras!

Featured Image Credit: Montenegro, Shutterstock

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