I know they are great alge eaters, I have had a couple and they ate hair alge, but I was just wondering if the toxins they relaese or the ink they release is going to wipe out my whole tank. I guess if that is the case, I was lucky the past few times, becuse nothing happened when they died. The one I got, the larger of the 2 stays on the glass, and hes moves around a lot, but the one is like in the entrance to a cave, down on the sand, with only his/her butt sticking out, so that worries me alittle, if it will release toxins if its dying. I don't really think its dying, because I put it on the rocks a few times, and it keeps going back to this one spot. Anyways, sorry to ramble on, just wanted to know any info about them. I have done reseach on them, but found cnflicting info, so I thought I would try word of mouth.