I recommend you keep every crappie you catch. they are big swawners and crappie spawn earlier than bass. There is enough time in between that crappie fry are large enough to eat bass fry when they are born. crappie will also compete with bass of same size for food. The problem with them is over time they can work the bass population down to almost nothing.
If your bass are difficult to catch and are looking overly fat you may consider adding some adult bass every 4-5 years. If you put enough pressure on the crappie (by harvesting them) you may not have to add bass.
Also, dont just go by a crappies color for identification. count the number of spines on the dorsal fin - if there are 5-6 dorsal spines then its a white crappie, 7-8 dorsal spines its a black crappie. I have seen many crappie that are almost jet black but were acutally white crappie.
I dont recommend crappie for stocking into small ponds. Dont play the catch and release game with crappie. over time, if left alone, they will probably crowd your bass population out. No matter what your bass will always be competing with them for a meal thus reducing overall bass growth.
