I have two 1100gr+ adults in 40g breeders and one juvie in a 20g. I have two hides, their water bowl, a large log and loads of plants taking up the vertical space. They aren't stressed, eat well, and can stretch at will which helps with that one lung thing. I don't see them often, usually only before feeding day and when they move to the other hide. I can't see fitting the hides and water bowl in a 20g and them having any room at all to move when they need to. I've tried it, went back. Just what works for us.