I was just wondering if anyone has any idea how long, roughly, you might expect an empty tank to remain cycled.

ie. taking fish out of a tank which has been cycled for about a year. Its a 10 gallon. I can't decide whether to put a new fish in it or such, but I figure the bacteria will start to starve at some point? I still have one fish in it but he is headng to my nice new 40 gallon to join his friends shortly.

I had kept him out of the 40 gallon as its new and cycling, and he had some swim bladder issues. When the new tank finished cycling tho its out of the old and into the new.

I guess it would depend on the filter size and media and such.

not a clue.
does it have gravel in it? any debris?
You could keep it going by adding a pinch of fishfood from time to time. The bacteria that eat debris in the tank produce ammonia. feeding them would keep ammonia happening. You could also add pure ammonia to keep the cycle.

Yes it has a good inch of gravel. I'd only need to keep it empty a week maybe I guess while I consider what/if anything I will do with it. I never thought of the food idea... wouldn't want to be much tho right or it would rot and send the tank levels way off?

if there are debris, ammonia is already being produced by the bacteria. According to Dr Tim, they produce a lot of the ammonia in aquaria. Yea, I'd just do a little pinch.