JABIII :

Welcome to the PB forum. It sounds like you have a nice lake to work with.

Do you have a water temp. profile and info on the lakes productivity (plankton bloom)? I ask because TS (threadfin shad) feed on plankton and have a low cold water tolerance (die off at 42 degrees). If you have trout that survive year round (indication of colder water) then you may have water to cold to support a year round TS population. If so you would need to stock them every year. That would be a big job for a 20 acre lake. There may be some other options which I will check on .In the meantime maybe others will join in with their opinions and you can read the link below on bluebacks and think about alewifes.

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=5;t=000411;p=1#000000