redearslider.com

Hi, My turtle Mikey is about 2 and 1/2 years old. His size is 5 inches. He is indoors in an aquarium. In the wintertime should I let him hibernate? Would that be in the aquarium or would I dry dock him for hibernation? Thanking you in advance for any information.

Reptiles don't hibernate, they brumate.

Some people decide not to make their turtle brumate because it can be difficult. So it is your call ! I decided not to as temperature never drops under 20 C here.
If you decide to make your turtle enter this state, I suggest you read this first: http://www.redearslider.com/hibernation.html

Thank you very much PokePony. Very helpful information which I will follow.