Couple of Things...
1. When water warms up, I have heard mentioned on this site about a food pellet shaped fly that people use to catch tilapia. You could use that to help deplete some of the ones you have that are a larger size. It would also be a fun way to catch dinner for yourself.
2. Yes, the bass look skinny, but as was mentioned by ewest, it could be the time of year. Check them this spring to see if they still look skinny or if they are fattening up. When the tilapia and other forage starts to spawn, they should fatten up nicely.
