Back when I had huge Niger cats I added a second one with my rays and the rays attacked it's fins. I know some bottom tank mates can work for some people but I've decided to leave the bottom strictly for the rays. Hope your irwini pulls through.
Hmmmm. Getting rays after the new tank is finished. That is one fish I had been considering for clean up work. What the heck, things happen in a tank of tetras too, just on smaller scales. Get it?