Silver arrowana is your best bet, though a black may work as well. Jars are notoriousely aggressive as a general rule so I'de avoid them. peacocks get pretty good size so i'de say maybe 3?.. Rays are challeneging but not impossible, I'de def do some research on each of these species in the sub-forums to get some more info. the sub forums can give you and idea on the sub-species of these fish as well and help you figure out what type/and how much you want to spend. spending an hour or 2 readin the stickies and threads will likely answer alot of questions on these fish. and give you some more precise questions to ask in reguards to them.