id wait a good month beofre you add any snails or crabs to your tank.. the rule that ive always been told is for ever 2 gallons you should have one blue legged hermit crab.. get those ones over the red legged ones cause they areef safe if you a reef tank.. worked at a pet store ppl always would bring the red ones back cause they are a little more destuctive..id also add a few brittle stars because they get under the rocks where your hermits cant get. cleaner shrip are always really good to add and they always are a great addation to the tank when new comers see them at work with your fish.. id add a pair.. and a coral band shrimp.. make sure you dont get two of these unless they are a mated pair.. they will fight in a 65 and you will only end up with one if they arent a mated pair. emeral crabs and sally light foot crabs are really good.. emeral crabs are cheeper and dont get as big as the sally lighht foots but both do a awsome job..