Both Rockbass and Pumpkinseeds are really cool fish, but they both also get big. Rockbass get to 17inches and Pumpkinseeds can get to 16 inches and are messy eaters......if your going to keep all of those to full size I would invest in a bigger aquarium.
"Pumpkinseeds reach a maximum length of about 16 inches (40 cm), although sizes of 68 inches (1520 cm) are more typical. Weights are normally less than 1 pound (450 g), although larger specimens can be encountered." ". A. rupestris, the largest and most common of the Ambloplites species, has reached a maximum recorded length of 43 cm (17 in), and a maximum recorded weight of 1.4 kg (3.0 lb). It can live as long as 10 years. These fish have the ability to rapidly change their color to match their surroundings. It is this chameleon-like trait that allows them to thrive throughout their wide range." Wikipedia.com Hoyo I have personally caught a 12inch pumpkinseed while fishing for Perch in Minnesota, and a good friend of mine has caught a 13inch Rockbass in the Gasconade river here in Mo (and has pictures to prove it). The world record 17 inch 3lb rockbass was caught here in Mo and several 16 inchers....Hoyo real sorry for ya if your fish are smaller in Wisconsin (kind of goes with what Minnesotans say about Wisconsin anyways Lol).
You really think you should keep 15-17 fish that can easily get 12inches but max out at 14-17inches in a 125g.....that are messy eaters?!?!? I wouldnt recommend it for the fish, or yourself if you care about your fish.