Get the temperature back up and see if it helps him to want to eat. As for how long until it is considered bad I am not sure. He doesnt leave anything alone in there without at least thrashing it a bit. He usually eats his Rats within about 20 minutes. Sometimes when he is forced to eat in the tub while we clean his enclosure he takes a bit longer but not usually.
Gators can go for extended periods of time without eating.
First thing I would do is to warm up his water. Get the temperature back up and see if it helps him to want to eat. As for how long until it is considered bad I am not sure. He doesnt leave anything alone in there without at least thrashing it a bit. He usually eats his Rats within about 20 minutes.