How Many Cory Catfish In A 20-Gallon Tank?

Hi, this is your friend Clifton Ervin, the founder and chief editor of this site, Aquariumwolf. I completed my graduation in marine biology and became...Read more

Cory catfish are growing in popularity among fish breeders. They make your fish tank lively as they are very active. Since they swim around most of the time, it’s important to put them in large gallons with sufficient spacing. So, you must first know how many Cory catfish in a 20-gallon tank to avoid overcrowding.

20 “1-inch long cory catfish” should be appropriate in a 20-gallon fish tank. The rule implies that a 1-gallon tank is ideal for a cory catfish of 1-inch in length. They are least active during the day but are most active at dawn or dusk. The most popular species are the albino Cory and the bronze Cory.

There’s a lot more to learn about cory catfish. So, read more below

What Is The Ideal Tank Size For Cory Catfish?

For a dwarf specie of Cory catfish, a 10-gallon tank may be ideal. However, a 20-gallon tank is recommended as it is large enough to contain a good number of Cory catfish. The number of cory catfish that can be inserted into a tank range from 20 to a hundred. The large tank is important because the fish is more active than others of its kind.

For more information on Corydoras catfish and breeding tank setup watch the following YouTube video.

How Many Cory Catfish In A 20-Gallon Tank Is Ideal?

A 20-gallon tank can comfortably house over 10 or 20 Cory catfish depending on their size. A general rule is that a 1-inch long cory should be kept in a gallon of water. This implies that a 20-gallon tank should contain 20 “1-inch long cory catfishes”.

How Many Cory Catfish In A 20-Gallon Tank?How Many Cory Catfish In A 20-Gallon Tank

For dwarf cory catfish, you may exceed that number a little. Ideally, we recommend 6 to 10 fish in a 20-gallon tank. This will give them enough space to maneuver and enjoy a habitat that closely imitates the wild.

Also, overstocking your fish tank may adversely affect their sexual maturity and active nature.

Requirements For A 20-Gallon Tank Setup For Cory

Cory fishes do not require a huge tank for their home due to their small size. Below are key things to look out for when setting up a 20-gallon tank for your cory.

Requirements for a 20-gallon tank setup

Tank Size:

Based on the small size of Cory catfishes, a 20-gallon tank is ideal for various species. A 20-gallon tank should contain a minimum of 6 fish. But put the fish into a tank with other species instead of putting it alone. It is recommended that the fish should be put into the tank in groups of 5.

Water Flow:

Areas with high water flow make the Cory catfish comfortable and happy. However, it is ideal to have a high and low water flow in your tank so that your fish can take turns resting in the regions they find comfortable.

Water parameters:

Wild Cory catfish tend to be picky when it comes to water parameters. Below are the ideal water conditions for a Cory catfish:

  • Temperature 70º to 80º
  • Alkalinity 3º to 10º dKH
  • PH 6.0 to 8.0

Watch the following YouTube video for 4 easy tank setups for a 20-gallon aquarium.

Key Characteristics Of Cory Catfish

The Cory catfish is easy to breed. This is due to their gentle nature, mild temperament, and unique characteristics. These features make aquarists love them.

Key characteristics of Cory catfish

Below are the key characteristics of Cory catfish:


The Cory catfish have a calm and peaceful demeanor which makes them very desirable. Also, they’re comfortable with other species of fish when kept in the same tank. They are usually not aggressive, which is why it’s not advisable to keep them with wild fish. Cory catfishes are well-mannered and active, earning them a place among social fishes.


Cory catfish have a lifespan of about 5 to 7 years in the wild, but they can live longer in captivity. So, in an aquarium, Cory catfish lives between 12 to 15 years. Moreover, there are rare cases of Cory catfish living for over 20 years.


Cory catfish can survive when placed alone in a tank. However, they thrive better when placed in the company of other fishes of the same species. You can also include other species of cory catfish in the same tank, but the tank must be large enough.

This will provide enough space for similar species to meet and school. They usually start schooling about 6 to 12 months after they’ve hatched.


If you compare it with a standard catfish, Cory catfish appear relatively small. Generally, their sizes range from 1.5 to 2.5 inches. Their size depends on the sex of the cory catfish. A female Cory catfish gets bigger as they grow older and can grow as long as 3 inches.

For more information on the 7 tips for keeping Corydoras in an aquarium, watch the following YouTube video.

Tank Mates For Cory Catfish

Cory catfish are comfortable with other fish species as long they are not predatory. So, for a fish keeper who wants to create a community, a tank mate is ideal for them. However, you must note that cory catfishes will only form a school with fish of the same species.

Tank mates for Cory catfish

Also, some fishes are too wild to be kept in the same tank along with cory catfish. Hence, we’ll mention some recommendable tank mates as well as those you must avoid.

Recommended Cory Catfish Tankmates

Below are recommended tankmates for a Cory catfish.

  • Gouramis
  • Danios
  • Platies
  • Neon tetras
  • Swordtails
  • Angelfish
  • Fancy guppies

Tankmates to avoid

Below are species of fish you should never put into a tank with a Cory catfish.


This species of fish is usually nippy. Despite being unaggressive, they take advantage of the calm nature of a Cory fish. This means they cause stress and compete with the Cory fish for food.


This species of fish are usually very aggressive and may end up eating the Cory catfish.

For more information on Cory’s catfish tank mates, watch the following video.

Cory Catfish Breeding Tank Method

To safely breed a Cory catfish, it’s ideal to put them in a tank. Important things you should include when setting up your cory catfish tank are a heater, air pump, and filters. Also, ensure that the bottom of the tank is bare and without substrates like sand or gravel.

Cory Catfish breeding tank method

The temperature and pH of the tank should be decided based on the species of Cory catfish. When the tank is set, the next step is putting a male and two female Cory catfish into the tank. If the temperature of the tank is below 65ºF, raise it to 72ºF (25ºC).

With the water conditions kept optimal, they should be able to mate.

Cory Catfish meals

A Cory catfish is naturally a scavenger. However, most of the meals in a tank usually drop to the bottom of the tank. Regardless of the leftover food, the fish owner should never assume the Cory catfish have gotten enough food.

Cory Catfish meals

A Cory catfish is omnivorous, so for a balanced diet, it has to be fed with plant and animal meals. Also, don’t overfeed a Cory catfish, as it will pollute the water with waste. This could be toxic to the cory catfish as they have a high sensitivity to ammonia and nitrates.

For more information on making sinking fish food, watch the following YouTube video.

Adding Plants To A Cory Catfish Tank

Cory catfish are shy and like to have plenty of covers around. Also, they need these covers to feel safe whenever they sense a nearby threat. Plants serve as one of the best covers that you can add to their habitat.

Adding Plants to a Cory catfish tank

Cory catfish is not selective of specific plants. Many aquatic plants can be used to groom your Cory fish. If your fish tank is placed in a location with limited light, below are some recommended plants:

  • Java Fern
  • Crypts
  • Hornwort
  • Java moss
  • Anubias Nana

For more information on feeding time in a Corydoras tank, watch the following YouTube video.

Bottom Line

How many Cory catfish in a 20-gallon tank depends on the size and specie of the cory catfish. If they are 1-inch in length, a maximum of 12 cory catfish will be fine. However, we advise that you keep the number fewer than this to provide enough room to scout around.

For tiny species such as the dwarf cory catfish, a few more fish will fit into the tank. However, this is not advisable. Although corys can survive independently, you should never put them alone – a minimum of 6 is recommended. For tankmates, angel fish and Gouramis are good picks.

Hi, this is your friend Clifton Ervin, the founder and chief editor of this site, Aquariumwolf. I completed my graduation in marine biology and became an Ichthyologist. One of my favorite hobbies is aquarium keeping; therefore, I love to talk about fish keeping, breeding, food behavior, etc., and much more relevant to aquarium maintenance. I have created this site Aquariumwolf, to share my 20 years+ of experience and knowledge with all new to this journey.

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