Here's a general guideline:
* Single Cory: A 10-gallon tank is sufficient for a single Corydora.
* Small School (3-5 Corydoras): A 20-gallon tank is recommended.
* Large School (6-10 Corydoras): A 30-gallon tank or larger is ideal.
Important Considerations:
* Species: Some Corydora species, like the Corydoras aeneus, can grow larger than others.
* Tank Mates: If you are keeping other fish, factor in their space requirements as well.
* Substrate: Corydoras require a substrate that is soft enough for them to dig in and sift for food. Fine sand or gravel is recommended.
* Water Parameters: Corydoras are sensitive to water quality. Maintain stable water parameters, including pH, ammonia, nitrite, and nitrates.
Remember: It's always better to err on the side of a larger tank. More space allows for better water quality and provides your Corydoras with more room to swim and explore.