I wouldn't worry too much about the bullheads. In a few years, when your blue cats get big enough, they'll eat the heck out the bulls, who are pretty slow. The ones that survive that will get big enough to actually eat...babies are too slow and become chum. You'll never get them all out, and even if you drain the pond, you need to let it dry COMPLETELY for a few weeks, because bullheads can survive for many days just buried in damp mud...they're tough.
Around here, no one wants them in a pond, but them 3-6" fish are exactly what the doctor ordered for bait for large cats. Let some kids (supervised) in to have a bullhead contest. Give 'em canepoles and 10 cents for each caught or just give em pop and have a weenie roast. You can keep them thinned that way, but won't get 'em all...just live with 'em.
'Sides, big 'uns are still fun to catch and look surprisingly good surrounded by hot oil.
[img]http://images.snapfish.com/33%3A%3B339523232%7Ffp45%3Dot%3E232%3C%3D847%3D556%3DXROQDF%3E232356695%3A539ot1lsi[/img]
