My New 300 gallon aquarium will be coming tomorow (in really crappy weather :/), and i will be adding my 2 Motoro Pair (still Juvies), 3 Arowanas, 2 Clown Knives, 1 Peacock Bass (no idea which kind), african arowana and an ID Shark. These will all be taken from my 125 as my 125 is extremely overstocked... and in the future perhaps a 500 gallon+... What is a good "clean Up" fish i can or should add into the group? I heard silver dollars are good. Are they really? please give some suggestions! and one that wont be eaten.