I can not tell you how many people I know in the last few months that have been loosing cresteds. A group of us privately suspect entamoebas as a matter of fact we are almost sure. When these strange deaths first started at the end of last summer I had fecals done on all of mine and no parasites were found though I e-fix mine once a year anyway. Do a search on entamoebas and see if this seems familiar at all. Cresteds are very hardy and never just drop dead though since last summer I can't go a day without hearing a story similar to yours. I am very sorry for your loss and if you guys have other rhacs please pick up some e-fix to be extra careful. You are welcome to PM for more info if you like, but this topic for some reason is being kept quiet so I will not go on too much.