I just got back from a 9 day vacation and my fish tank seemed fine except for the fact that my one guppy seems to have fallen off the face of the earth. I checked everywhere for him, in the filter, behind the tank. etc. but there is no trace of him. The rest of my fish are fine, and this guppy showed no signs of distress before I left so I'm not sure how he would have died. I've heard of fish disappearing before but it just seems really strange.