I'm no expert but here are few images. First one is a school of sand bass chasing a school of shad.
This second one is a mess of sand bass off the bottom. I didn't have the depth range dialed in so it repeats with a second echo below it in less detail.
You can see my lure dropping in to the school on this one.
Side scan with the bottom loaded with fish.
If you see this get your lures in the water, its game on.
I use a Huminbird 998.