When I bought my live rock I got probably close to a dozen hitchhiker aiptasias. I just set the tank up and it is still cycling so it really isn't doing any harm in there now so I would rather not take the rock out. I read that peppermint shrimp will eat them. How many would I need for a 29g? I wanted cleaner shrimp anyway, but if these guys eat the aiptasia are they are going to eat stuff I want later? Somebody also told me that red legged hermit crabs would eat it. Is that true? Are they are better option than the shrimp? Thanks!