Aquariums: My fish are swimming in circles around my window scraper

I have the Oase magnetic one. I just have in in the water and clean it occasionly. Is that bad? Should it be outside of water when not cleaning? Is it bad for my fish to swim kn circles like that or are they playing? They seem completely fine, its just sometimes theyll go over there and it it for 30-60 min before moving on and doing something else