Hi how interesting. I have almost the exact same setup as you,125 gal jardini arowana 15" oscar 9" 9" megalodoras 3 7" albino redtail tinfoils an 8" goldie and a 6" gold phantom. Nothing bottom dwelling is touched but my oscar was bullied into a corner all day and one of the tinfoils was getting bitten everywhere. Had to give oscar to lfs, and am trying to sell tinfoils. Anything bottom dwelling seems fine, for now. How big is your jardini? By around 10" but definately at 12" they will kill anything mid-dwelling, and mines not the only one. Before i sold the oscar the oscar was 3/5 the size of the aro. When fully grown not only does the agressiveness become worse but the aro will be twice the size of the oscar.