crappie_hunter15,
There are several possibilities why your pond may be over run with small bass. Underfishing can be just as bad as overfishing for a pond. Left unchecked, bass populations will increase to densities that inhibit good growth rates and most of the fish will remain small (stunt). Too much vegetation in a pond can also be a problem for the bass as it provides too much escape cover for prey and reduces the ability of the bass to catch a meal. Lack of sufficient food will also cause poor bass growth rates. You mention that the pond has "bass, catfish, and possibly some species of bluegill". For new pond stockings four species of fish are recommended. These are largemouth bass, channel catfish, bluegill and fathead minnows to jumpstart the forage base. If you are not sure about what sunfish/bluegill are in the pond you need to find out. "Full blooded" bluegill are recommended for Kansas ponds as they provide reliable, long term forage for the largemouth bass. Many pond owners want "hybrid bluegill" and some fish dealers are good at 'pushing' these fish to pondowners. The problem with hybrid sunfish is over time they will decrease in density and not provide adequate prey. Hybrid sunfish can be used to compliment the sunfish population in a pond but full blooded bluegill should be present. Other sunfish may compete directly with young bass and reduce growth rates. Green sunfish are common in Kansas ponds and they can actually become the top predator and suppress bass growth. Having all green sunfish and no bluegill would possibly explain the current condition of your bass.
Once you figure out what fish you are dealing with and the status of your vegetation you can begin to look at selective harvest or supplementally stocking species (bluegill) that may be missing from the pond. You need to have a good balance of bass and bluegill before you even consider stocking other species in to the mix. The addition of crappie too early can cause serious problems. If the bass population is not 'strong' enough to adequately prey upon young of the year crappie then the crappie will quickly overpopulate and hurt the rest of the species in the pond through competition. If you decide to stock crappie only stock black crappie as they are less prone to overpopulate. It is difficult to manage for trophy bass AND trophy crappie. For trophy bass management a pond owner needs to create a bass population with a low density of large bass which requires selective harvest of the 'medium' and 'small' bass so that the larger fish continue to have the resources to continue to grow.
A pond can't support HIGH density of LARGE individuals as there just isn't enough forage to feed all those big fish. Kansas farm ponds can produce approximately 300 lbs of fish per acre, you as a pond manager must decide what the species and size composition of the 300 lbs will be.
Big bass like to eat big meals. Having big bass that are capable of eating crappie >8 inches doesn't do well in producing trophy crappie. In order to produce trophy crappie the bass population must be managed for high density small and medium sized bass (up to 13-14 inches). The bass will need to be 'intentionally stockpiled' to create many smaller hungry mouths that prefer to eat SMALL crappie instead of BIG crappie. By controlling the recruitment of young of the year crappie to the adult population the remaining crappie will be allowed to grow in to larger sizes (trophy sizes). Once the crappie reach ~6inches the smaller bass won't be able to eat them and can grow larger with little competition from other crappie in the 'low density' population.
I'm getting pretty wordy here but in short, take inventory of the fish species present and get an idea of their density. A few trips with rod and reel, ruler, and recording catch and length data will give you an idea of what you are dealing with. If you have adequate forage and all your bass or small then you will need to remove the most common size to allow those remaining fish to grow larger. Catfish can be harvested as desired. Channel catfish usually require supplemental stocking in small Kansas ponds as the bass will limit catfish recruitment. Keep notes on catfish catch rates. When catch rates get too low it's time to restock.
Here's a link to pond management on the KDWPT website. POND MANAGEMENT IN KANSAS You can also contact your local district fisheries biologist for more info.