So I'm thinking about upgrading my betta fish's bowl into a 5 gallon tank. The tank used to belong to my hermit crab about a year ago, and I am able to clean it out and make it my betta fish's home. Is it safe to do this when I had a hermit crab in it before? I know I shouldn't use soap to clean it out because it can make the fish sick, but I don't know how I'd be able to sanitize it from the crab. Is this a safe thing to do? If not, I was just going to buy a new tank.