I just recently came across these fiberglass tanks with the window in front. I'm going to buy one, but it will be ugly since it will be bright blue. So I'm going to make an enclosure out of 2x4s and wood paneling to cover the blue. Here are my sketches. The last one is the tank I will be using.
diy filter out of a 20 gal rubbermaid tub, also in a 2x4 wood panneled enclosure, with a stock list of medium catfish, unless you decide to go the larger tank route, then l would say larger catfish, with an assortment of larger cichlids