I have a 180 gallon (6x2x2) aquarium I am converting to a stingray tank. I want to keep 2 leopoldi, a silver arowana, a couple of geophagus and maybe a couple of clown loaches. I saw that someone on the fourm has small leopoldi available and want to start with small ones. I know the leopoldi will eventually outgrow the tank, but how long should I expect to be able to keep them in this tank before moving to a larger one?