Finalising stock for 260 gal

84x30x24" 260 gal is coming next month, already have an Oscar, Vieja Synspilum, 5 Silver Dollars, Senegal Bichir, Endli Bichir, BGK and a lone Geophagus Surinamensis (had three, two larger ones died due to stress from travelling). Any suggestions for additions? Would really like a larger fish in the tank, even if it meant moving some of the others to my 90.

Thought about a flagtail but i've heard they're known for sucking slime coat off of bichirs? Not too sure, would just like a larger fish in the tank as that was one of the reasons I decided to buy 30" wide tank.

I like the arowana idea but some people have said a 84x30" footprint is too small.. If possible i'd like to move all of these fish over to the 260 but don't mind putting some in the 90 if they wouldn't work with the larger fish i'm looking for.

Would adding a Jag be asking for trouble?