Seemed a bit foolish to me for the same reason I gave before, health. Do you know why the discus was sick, If it was tb, aeromonas, or flagellates then you and your nieghbor will soon have sick piranha, considering the price of an elong it seems that you may have more money than sense.
It would seem your "experiment" has simply confirmed what has already been tested many times, elongs don't play well with others. Another "experiment" that will probably give you a predictable result is sticking your tongue in a live light socket. My prediction is that you will get shocked and that it will hurt, but feel free to test it if you so desire. After all, it might be different for you, you might be "special". If you do this please post pics.
I make no condemnation over feeding one fish to another except that I might rather have the fish myself, however...,
The way you went about introducing this thread seemed to be deliberately phrased to encite flaming. That is called trolling and while it may be a way for you to get a little amusement into your otherwise possibly dreary existence it is not something that is appropriate on this forum.
Please find a new way to amuse yourself.