I wouldn't do anything too much smaller than the one you have now. My female is probably about that size with my male running behind at about 2" in length. I have them both in a 24x18x18 tank (should have gone with the size you have though). I am always looking to add another one (or two). I am not sure about any online breeders/distributors as I get mine from a place in California through the pet store I work at. We order our animals from Pet-Tech Products, but they do not sell to the public. =/ I have heard lots of good things about JoshsFrogs though.