Fowlr aggressive tank

Was thinking about setting up an aggresive tank (triggers, eels, puffers, etc) and was wondering what the smallest size tank that would work? I know bigger is better, but I don't have too much room. Wouldn't mind only having 2 or 3 fish so doesn't need to be huge. I'm probably not making any sense, y'all are probably saying just buy a 125 and go with it. Honestly idk if I could afford that big of a tank. Maybe if I took it uber slow? Just wondering what y'all thought...