Whatever they can fit in their mouths?

Seriously, I think yellow perch are the main forage fish, along with young bass, crappie and squawfish. But mostly perch. I've caught bass and crappie that were coughing them up on the way in.

SW Idaho gets the long, hot summers warmwater fish need to grow to respectable size. Both fish were caught in the same reservoir. I've also caught 24"+ rainbows and 10" bluegills out of the same water.