How Many Corydoras in a 10 Gallon Tank (40 Liters) Should You Have? - "Corydoras julii" by Kai Schreiber is licensed under CC BY-SA 2.0.
How Many Corydoras in a 10 Gallon Tank (40 Liters) Should You Have? - "Corydoras julii" by Kai Schreiber is licensed under CC BY-SA 2.0.


When it comes to setting up an aquarium, one of the most delightful species you can choose to include is the corydoras, often known as cory cats. These small, peaceful bottom dwellers are not only known for their charming looks and behaviors but also for their tank-cleaning abilities. However, one common question that arises for enthusiasts is “how many corydoras in a 10 gallon tank (40 liters) can I have?” This question is crucial, not just for the well-being of the corydoras themselves but also to ensure a harmonious balance with other potential tank mates. In this guide, we will explore not only the answer to this question but also how to create an ideal environment for corydoras and their companions.

About Corydoras

Corydoras, often affectionately called “cory cats” or “cory catfish,” are delightful little creatures that grace many freshwater aquariums. These small, bottom-dwelling fish are members of the armored catfish family and are known for their peaceful nature and distinctive, charming appearance.

Corydoras have a wide, flat body that’s perfect for their bottom-feeding lifestyle. Their armor-like skin is actually made up of two rows of bony plates running along their sides, which is where the “armored” part of their name comes from. This feature, combined with their barbels (whisker-like appendages) around the mouth, gives them a unique and somewhat endearing look.

One of the most captivating aspects of corydoras is their variety. They come in a range of patterns and colors, from the classic peppered cory with its speckled, greyish body to the vibrant bronze cory, and even the strikingly patterned panda cory, which sports large, dark patches over its eyes and at the base of the tail, reminiscent of a panda bear.

Behavior-wise, corydoras are the epitome of community fish. They’re not only peaceful but also sociable, often seen interacting gently with other tank mates. They have a charming habit of sifting through the substrate (the bottom layer of the aquarium) with their barbels in search of food, which makes them excellent at keeping the tank clean. Another endearing trait is their activity level; corys are quite active and can often be seen dashing up to the surface of the water for a quick gulp of air before darting back down to the bottom—this is perfectly normal behavior for them due to their ability to take in atmospheric air.

Corydoras thrive best in groups, as they are schooling fish by nature. Watching a group of corys move together around the tank can be both calming and mesmerizing. They communicate with each other using a unique method: they click their pectoral fin spines as a form of social interaction, especially during feeding times or when they are excited.

All in all, corydoras are wonderful additions to any freshwater aquarium. Their peaceful demeanor, social nature, and fascinating behaviors not only make them easy to care for but also a joy to observe. Whether you’re a seasoned aquarist or new to the hobby, the humble cory catfish can easily become a cherished part of your aquatic family.

How Many Corydoras in a 10 Gallon Tank (40 Liters)?

When thinking about how many corydoras to keep in a 10-gallon tank (40 liters), it’s important to consider both their needs and the space limitations of your aquarium. Corydoras are sociable little creatures that thrive in groups, so ideally, you’ll want to aim for a small school to keep them happy. Given the size constraints of a 10-gallon tank (40 liters), you could comfortably accommodate a group of about 4 to 6 corydoras, depending on the species and their adult size. Remember, some species of corydoras can get a bit larger and would require more space per fish.

However, when considering tank mates, it’s crucial to account for the bioload – essentially, the total amount of living organisms your aquarium can support without becoming unhealthy. Every fish adds to the bioload, requiring more filtration and water changes to keep the environment clean and balanced. If you plan to have other fish or aquatic animals in the tank along with your corydoras, you’ll need to carefully select species that are not only compatible but also small enough to ensure the tank doesn’t get overcrowded.

Aquatic plants and decorations take up physical space, too, but they can also improve the quality of life for your corydoras by providing hiding spots and enriching their environment. Just make sure that the overall setup leaves enough room for all inhabitants to swim freely and for adequate filtration.

In essence, while you might be starting with the question of ‘how many corydoras in a 10 gallon tank (40 liters) should I have?’, the answer ties into a broader consideration of the tank’s ecosystem. It’s about balancing the number of fish with the available space, ensuring the water quality stays high, and keeping the environment enriching and stress-free for all the tank’s residents. Always monitor the tank’s parameters and be prepared to adjust your plans as your aquatic community grows and changes.

How Many Corydoras in a 10 Gallon Tank (40 Liters) Should You Have? - "Corydoras julii" by Kai Schreiber is licensed under CC BY-SA 2.0.
How Many Corydoras in a 10 Gallon Tank (40 Liters) Should You Have? – “Corydoras julii” by Kai Schreiber is licensed under CC BY-SA 2.0.

Tank Setup

Setting up a 10-gallon tank with corydoras and their tank mates involves a thoughtful approach to ensure all inhabitants have enough space, proper water conditions, and an environment that mimics their natural habitat as closely as possible. Here’s a step-by-step guide to help you create a thriving community aquarium:

  • Choose the Right Substrate: Corydoras are bottom dwellers with delicate barbels, so it’s essential to use a soft, fine substrate like sand or smooth gravel. This prevents damage to their barbels as they sift through the substrate looking for food.
  • Add Plants and Decor: Live plants not only enhance the visual appeal of your aquarium but also provide hiding spots for your fish and help maintain water quality. Consider plants like Java fern or Anubias, which are hardy and easy to care for. Decorations like driftwood and caves offer additional hiding places, mimicking the corydoras’ natural environment.
  • Water Conditions: Corydoras thrive in slightly acidic to neutral water (pH 6.5-7.2) with a temperature range of 72-79°F (22-26°C). Ensure the tank is fully cycled before adding any fish to establish a stable nitrogen cycle, reducing harmful ammonia and nitrite levels to zero.
  • Filtration and Aeration: A gentle filter that doesn’t create too much current is ideal for corydoras, as they prefer calm waters. Make sure the tank is well-oxygenated; a sponge filter can be a great choice, providing both filtration and gentle water movement.
  • Choose Compatible Tank Mates: Since corydoras are peaceful fish, select tank mates that share this temperament. Small, peaceful fish such as neon tetras, guppies, and cherry barbs can be good companions. Avoid aggressive fish or those large enough to view corydoras as food.
  • Feeding: Corydoras are omnivores. Offer a varied diet of sinking pellets, flakes, and frozen or live foods such as bloodworms and brine shrimp. Ensure food reaches the bottom of the tank for your corydoras to find.
  • Regular Maintenance: Perform regular water changes, ideally 10-20% weekly, to maintain water quality. Test the water parameters regularly with a test kit to keep an eye on ammonia, nitrite, nitrate, pH, and temperature levels.
  • Observation: Spend time watching your fish to ensure they are healthy and interacting well with their tank mates. Healthy corydoras are active, have good appetites, and show vibrant colors.

By following these guidelines, you can create a comfortable and stimulating environment for your corydoras and their tank mates in a 10-gallon tank. Remember, the key to a successful community tank is research, preparation, and regular care to ensure all inhabitants live harmoniously together.


Understanding how many corydoras in a 10 gallon tank (40 liters) you can have, is the first step towards creating a vibrant and healthy aquatic environment. While the specific number can vary based on the species of corydoras and the presence of other tank mates, aiming for a small group within the recommended guidelines ensures that these delightful creatures have the space and companionship they need to thrive. Remember, the key to a successful aquarium is not just about how many fish you can fit, but about creating a balanced ecosystem where all inhabitants can live in harmony. By considering the needs of your corydoras, choosing compatible tank mates, and setting up your tank with care, you’ll create a beautiful underwater world that’s a joy to observe.