Although carp are generally called "bottom feeders" here, they are pretty much omnivorous, and the best bait for catching them on a hook-n-line is fresh corn. They will take worms or rotten stuff off the bottom, but actually prefer "fresh and tasy" veggies, if you're fishing for carp and don't want to deal with the other true scavengers.

On a quiet lake, you often here mysterious "slurping" that's usually the carp sucking algae (nice fresh stuff) off the surface in the shallows. Their relatively clean diet makes them - usually - much milder flavored than some other fish that do feed on garbage, or even the carnivorous ones that just eat a lot of meat.

In the acquarium, or pool, the carp (a.la. goldfish or koi) need a low protein diet, compared to most fish, and that makes for a lot of extra sh*t, which gives them a reputation for "mucking up the tank;" but "on the inside" they're pretty clean. (and tasty)

John