A few days ago I got two iridescent sharks and one of my oscars bit one of their heads off, I came home and it had a perfect bite hole
if a fish will fit in its mouth yes a Oscar will try to eat it . my mouth dropped when I saw it said it bit its head off
glad to see the shark swimming around , the thing that confused me is Oscars have no teeth , they chew with their inner gills that shark was lucky he was big enough not to make it to those gills.
the shark may have bruising from the Oscars jaws if it's still swimming around he probably didn't sustain no internal injuries,
I had many of those iridescent sharks in the past they never seemed to hid in decor ect they always stayed out in the open also had Oscars ,
now that the Oscar attempted to eat it with no success he will most likely not attempt it again , but it does sound like your Oscars are wanting some feeders .
these iridescent sharks are not a aggressive fish and basically can't defend themselves from predators as you had found out , they do best in tanks with any type large of non aggressive fish these sharks are not carnivores there vegetarians .