We had a big aquarium but the cats weren't interested.All that work and they didn't care.LOL.But I think the cats like smaller ones better where they can sit in front and watch easier.We also have the Cat Nip Video like Catmandu and when I put that video on they are all quiet in the livingroom watching it so I can get my cleaning done.Just like human children.Keep them occupied to get work around the house done.Too funny