So I've tried twice to keep an emrald crab to help with some alge/dinos/whatever and they don't last all. my parameters are pretty constand, I don't have any problems with my fish or other inverts and most of my corals are doing great with a few just not growing at all. I feed dry flakes everyday and I just started micis every other day. the first crab lasted a coupld of weeks but this second one didn't even make it a week. wtf?