Bass feeding on top?

[iowathode]

First of all, hello all. Yep, I'm a newb.

I've been following this website for quite some time (love it btw), and I finally decided to take the plunge and join the forum to seek some advise. So, I'm starting off with this question. I asked this question in my other forum, but didn't really get a satisfactory answer. So...

I was out fishing this morning at first light and all of the sudden when it got just bright enough to start seeing decently, the water started to come alive. Let me explain... Bass were smacking the top of the water, but for the most part they were sucking something off the top of the water. They'd come up and sort of porpoise (however you spell that), so you could see their backs and fins. They were doing it all over a large flat that was anywhere from 5-9 feet deep. I threw everything I had at them, sort of. I threw a spinner, a buzzer and shallow diving crank (because they were obviously hitting the surface), but couldn't get a single strike. The bass were obviously active, so what gives? The only thing I can think of is maybe swimming a jig or swim bait, that might have been the ticket, but other than that I'm totally clueless. I've had this happen before in the evening when bass were actively feeding and had the same dilemma. So how do I tackle this? It's really getting to me not knowing how to catch these active bass. So, I'm hoping that some of the bass experts out there can help me figure this scenario out, or at least shed some light on it for me.

Extra info:

Central Iowa
water temp 80 degrees
water is stained to clear

Thanks in advance for any help offered.