I have a 10 gallon aquarium and was wondering if I would be able to keep one discus in it. I’ve done some research and found that this may work as the general rule of thumb is one discus per 10 gallons.

Get a bigger tank or research fish more appropriate for a 10 gallon. My first discus tank was a 75 gallon. Every one starts out somewhere in this hobby and asking questions online is where I started but anyone can say anything and I found the best sources of information was books written by experts not some guy that watched a YouTube video and thinks they know everything

I have a few discus and yes that's a rule of thumb but there is also a minimum size which I would say is a 30 gallon tall but in that you could have a breeding pair personally I would go with a 40 gallon at least so they have some space. A discus can get up to 8" round so you can imagine in 10gal tank that is 12" or 13.25" wide that would be a tight fit for that fish.