So, he use to eat mysis and brine, then ate a maroon and now won't go back to mysis and brine but will eat hunks of krill that you bring down to him?
It's because he knows a good thing when he sees it. He really doesn't want to chase after small bits of food like a mid water column fish... he wants meaty hunks and would prefer to sit on the bottom or in a cave and wait.
How long ago did he eat the maroon?
Have you tested your water lately? Some of my guys are nitrate sensitive and will go off food, or not take it as well, if the nitrates climb. The cloudy eye could also be a sign of declining water quaility... easy enough with scorps.
Have we talked about your scorp before? It's a Brasiliensis like mine.