Hi everybody! I was just wondering if a hamster/frog/general aquarium tanks would be suitable to keep a betta fish in. My boyfriend has two aquarium tanks (one five gallon and one ten gallon) that he used to keep a hamster and a frog in and I was wondering if they would be okay to house a betta fish. I don't know even if I sanitize the tanks if they would be safe for a betta. If so, how would I properly sanitize them? And what other supplies would I need? A heater? Filter? And also, how would I change the water in these tanks? Thank you!