I have to agree about the 2 pairs of clowns. I had the same setup in my 6 foot 125g tank and after a few months of bliss the one set decided out of the blue that they had to kill the other pair. This all happened in a days time and luckily I had a place to put the other clowns. I have zero doubt in my mind that the one pair would have been killed.
It may work for awhile but it usually ends in mad aggression. Just a heads up!
And I would watch that butterfly, they are notoriously difficult to get eating. I lost one after about a month of it eating fine and doing well out of nowhere. :-(