agreed with the last couple. than tank is incredibly too small to even think about an aro, and a clown knife as well. as far as him "eating" them, i doubt the ghost would last very long, i had a clown in with my silver and it was fine. u will prob have more luck with a silver than a jar. its hit or miss sometimes man....... but if u dont get a bigger tank--->
both the clown and the aro will probably be ABLE to eat the bgk but if they will do so or not is up to them.. quite simple.. I would personally actually risk it since my experience with these species are that it will work.. (and I have done it)..