I have a 100 gal reef and I got hermit crabs and and emerald crab before I got fish. They ate all they could and when they ran out a few of them killed each other before they were balanced out, but I still have about 80% of the ones I bought, and when my tank got established I had to get more. I have heard that you get 2 dwarf hermit crabs (blue legs) per gallon of water, but I think if I had it to do over I would have cut that in half and worked up. Hermit crabs are great, and I love the emerald crab. If you find you don't have enough for them to eat you can freeze a few pieces of romain lettuce and then rubber band some to a rock so it sinks. Remove the light green core parts so all they have is the really dark green part. They go crazy for it. It's kinda funny too!
