The frogs do stay in the water. but they frequently dart to the surface to gulp air. They also seem to prefer to squeeze under something like a log. An air stone or curtain would be cool. The lid is good. They cling or brace on things and do that at the surface. They could crawl out without the lid. I always get an Oh! You have frogs! when people see them. But of course they are in a very active set up. If you are going to keep them separate, you could consider African Clawed Frogs--Bad Boys! I don't have them, but they are like having puffer fish of the frog variety. Although they may get bigger. You'd have to research.