If you're not medicating your tank, yes. They say it takes about 1 month for the ick life cycle to complete, without host they will die. I don't think crabs are host for them. Let them stay and continue to forage on some algae on your LR.
Yeah you can leave them in without medications. Ick takes about a month (either 21 or 23 days to be exact). Ick will stay in the shells but won't effect inverts.
No! They need a host ie... a fish. Thats the only good thing about those nasties. If you don't have a host for them, they will starve to death. Yeah!!!!!
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