Well all of my mantis' started freaking out and doing flips all around the tank and stuff about a day or so before they died, Hope this doesn't happen. Actually I also found a small eggcase kind of a leathery type texture to it, and was covered my the Aragonite bottom of the tank. it was about the size of a quarter and oval. ALSO, somehow my blenner got sucked INTO my powerhead. I don't know how he managed ot do this, the part where it sucks water in is too small for him to fit, and i ahve it pretty high to give my Xenia enough filtration. 3things, 1 night, 1 tank........ I'm getting confused here