they can handle anything from 40F to 80F, Below 55F they can no longer digest food properly and it rots in there guts, above 70F oxygen levels in the water get to low for larger fish. Below 40F (a temperature it never gets at the bottom of a pond unless the ice reaches all the way to the bottom) they have alot of trouble and die within days and above 80F there metabolisms are going so fast that they get there water really really dirty. Idealy you want to be inbetween 65F and 75F and Airate the water if it is above 70F especially as your fish grow past say the 6 inch mark.
HTH
Opcn