This is not ich, and is likely bacterial. The fact that the death count is so high and in multiple species leads me to believe there is a water quality issue. What are your water parameters, what fish are in the tank, and what fish have died? What is the size of the tank and what filtration are you using? What is your tank maintenance schedule (water changes, gravel vacuuming, filter cleaning, feeding schedule, etc)?
I would start by cleaning the gravel, cleaning the filters, and doing a large 50%+ water change. You should also lower your temperature back to below 80.