sorry i posted this two times. moved from a 20 gallon to a 55. he is approx. 3'4" not too big around tank is 85 i didnt know i should measure the humidity. ill have to take a trip to the store. but his tank is in the living room, could that be a problem? one side is his hide with heat under and above other side is water and cooler. half logs in the middle for extra hides. mice were large. the rat i offered was small/med.