I'v got a 60gallon tank that i'm trying to cycle and I'v put a giant gold fish in there to get the job done even though it should be already cycled I dropped the fish in there to produce what I need and I put it up in a basement where there is just one window that gives off little light. should I add a light to the tank or is the little bit of light coming through the window enough?

They don't need any light... lots of fish survive naturally getting less than 1% sunlight...