I keep freshwater aquariums, and like invertebrates. I’ve never kept salt before, but I think they’re pretty. I know the larger the tank the easier it is to maintain, but I want a blue leg hermit crab or two and that’s it (are they social? I only want one but my land hermies are social). I was thinking those reef jars are pretty, but pretty small, too. How many gallons would you recommend for a single blue leg hermit crab (or two if they’re social)?