I haven't taken them out for a while at this point (it's been fairly cold, and the apartment heat is set to 70F), but when I did take them out I would take them out a few times a week. I'd leave them in the Rubbermaid (together) for an hour or so. It was really nice to have the gym when I was doing my last deep clean - that way I could keep the ISO empty in case of any molters I might find. One other thing - somebody asked if crabs have memories, and a study on marine crabs found that they do have memories. See this story for more details - http://www.cnn.com/2009/WORLD/europe/03/27/crabs.memorypain/index.html?iref=allsearch. On that note, crabs can be trained to come out when called by their names, so how could they do that without a memory? Or how could crabs become used to being handled if they couldn't remember being handled?