ya state law here is you can keep any game fish of any size for bait, but its a grey area because they have no idea what size bait I need lol so keeping fish in a tank at home is by all definition legal for me. I did talk with the CO that patrols this jurisdiction about it, he basically said he doesn't care what I do as long as I'm not taking undersize fish to eat lol.
You can only keep Gamefish of LEGAL SIZE for any purpose. Recently PAFBC made it legal to use gamefish as bait BUT they must be obtained legally, which of course means legal size and creel limits apply.
FYI, just so you don't get in trouble, re-read the book that they hand out when u buy a fishing license, "2016 Pennsylvania Fishing Summary". It is free and it is MANDATORY that the clerk hands it out w/ the purchase of a license, if not they can be fined for it. I'm always giving that idiots at our local Wal-Mart a hard time about it because they NEVER pass them out and there's a lot of important things people need to know in it and hopefully it will help our already-dwindling fish populations if people have it easily available for reference.
Oh, anyway sorry about the derail OP, i just wanted to make sure my buddy didn't get fined for mis-interpreting the rules.....it's not always easy to understand them as they are written a little confusing sometimes.
Anywho, i was never a huge fan of Greens, i generally target them when i need bait because they are so aggressive and prolific breeders and compete w/ Bass and gamefish for food and territory, usually winning. Rock Bass as well, but they DO look really cool in a tank.
I think i like Pumpkinseeds, also the Redbreast, and i bet a Redear/Shellcracker would make an awesome pet