There are two types of grass carp, the regular wild type and a specially treated sterile type. Some states allow both, some states allow neither, some only allow certified sterile type. Check out the Missouri law before proceeding. Most states also have pretty strict limitations on what you can stock on your own into any state water. You generally need a permit that may or may not be hard to get for the species you wish to introduce, depending not only on the state, but generally also on the general watershed involved.