I have a Ropefish (I plan on getting another one) and three Port Hoplo Catfish in my 55 gallon,as well as a small Pleco. All these fish get along great, but, unfortunately they all frequent the bottom of the tank and aren't spectacularly colorful. Does anybody have any suggestions for a fish species that would do well in this tank and likes to hang out in the middle of the water column? Aggressive, semi-aggresive, passive. It doesn't really matter. Just so long as its big enough to not be eaten and stays small enough to prevent overcrowding when the ropefish and catfish grow bigger.