With good aeration you're probably fine in a 40 breeder or larger. Remember how cold they like it. My LFS tried keeping them in tropical temps and they all died.
They can be kept in higher temps provided the aeration and filtration are overdone to the point of ridiculous. These cats come from very fast moving (whitewater rapids) waters. They evolved in an environment of very high dissolved oxygen. If you can provide that, you're giving yourself a good shot towards being successful with this species.