Depending on the species and the strain, trout can survive temps into the 80's. Preferred temps are the low 60's with 70 degrees being the cut off for comfortable... DO is also highly important in trout survival.
With all due respect CJ that survival thing at higher temps that is published for some species of trout is way overrated unless you're talking about some of the native desert trout of the west. I'd like to see any trout survive a temp into the 80's for more than minutes. If my trout pond water got to 70 I'd be expecting disease problems and eventual morts.
