Suckers make excellent crawfish bait. And crawfish make excellent dinner. A fresh sucker in a crawfish trap can really bring the mud bugs in. Put a half a sucker in a trap or use a small sucker with slits cut into the flesh.
Depending on the size of fish, dig a hole and let them decompose a month or two. The hole should be big enough to bury the fish with a few inches of soil on top to keep most animals from digging them up). Turn the soil before planting.
Some of my buddies in Weld County swear by this and have the State Fair ribbons to prove it.
Carp are also the #2 game fish in the world but with all the fantastic sport fishing in this state, the carp have gotten a bad rap.