My 3 fiddler crabs are alone in their own tank, and I have a half land/half water setup. They frequently come out of the water to hang out on the beach. The boys love to wave their big claws around and try to impress Princess, the female! I also have made the water slightly brackish, adding 1 teaspoon of Oceanic sea salt mix per gallon, as they are not a truly freshwater creature. Mighty cute and interesting!