Cotton mouth, I have just inspected my tank like there is no tomorow, one of my guppies has cotton mouth, this is possibly whats killed my other fish as they all slime over when they die so this is a symptom i would have easily missed after death, this been an aggressive (parasite?) would have caused the fast deaths. so for the next week i will be using melafix and cranking up my water changes. If anyone has a better treatment for this I would really like to know as I do not want to loose any more 
Looks like the ornomant may not have been the cause

Looks like the ornomant may not have been the cause