Get a heater guard, if your heater doesn't have one already.
A lot of catfish to take to sleeping on or around the heater (no one seems to know why, but they do!) and the trouble is, if the heater switches on, they don't always feel the heat until it's already burnt through their scales. I've seen some very nasty heater burns on fish, sometimes fatal.
If you already have a heater guard then you're fine, your pandas won't come to any harm.