hmmmm.i see fish hide behind a heater all the time and they dont get hurt.and yes ive felt a heater on before,yead its hot.accidentally touch it while doing something in the tank.
I had tire track eel that stupid as all hell and wrapped himself around my heater and kicked it there till he had to peel himself off.When it started to heal up he would do it again.
He's gone now,good riddance...last eel I'll ever own,mark my words.
my pleco of over a year dies about 3 weeks ago from a heater burn, It CAN kill fish if its bad enough, My other pleco got burned before but It healed fast and with no complications, but this one was really bad, think he got wedged behind it
from experience, taking the heater out thinking its unplugged when its not, you realize real quickly how hot they get if your directly on them. Most fish don't stay on there long enough to get burned, but thats not always the case.