It would appear that one of the black neons has disappeared in the night. I must assume he's been taken, but there nothing left of him at all... not really a big surprise, seeing as he ate his own molting a few weeks ago...
Originally posted by Traci
Your cray wasn't playing dead, it was searching for oxygen. Crayfish need very well oxygenated tanks. The agitation from the filter output won't be enough. Do you have airstones or a bubble wand? They will lay on their sides in order to absorb more oxygen into their gills.