Should I help them by putting some chicken or liver in once a week? If so how much would you think they would need per week? Or just let them be. Or recatch and eat them an shut up.
Those critters are going to want to eat, and IMHO they will eat at the detriment to your BG and LMB. They will also eat your small and medium sized BG and LMB. Much like pet alligators, when they get to that size, they become problems.
If you feed, I'd use floating pellets. The pellets are a lot cheaper than liver or chicken, and they are designed for proper fish nutrition. The catfish will quickly learn to suck pellets like giant vacuum cleaners.
Don't get me wrong. I love to feed, watch, catch, and eat catfish. But, big ones are nothing but problems.
I'd have these guys for lunch -- at least the 28-incher.
If you want catfish, I'd suggest getting some younger ones (6 - 12 inches). They're cheap (about $0.50 to $0.75 each, in this area). Each year, put in about twice as many as you would like to eat the next year. Pull them out when they get 15-20 inches.
One other caution -- catfish are smart and savvy. They become hook shy real fast. They have reasonably long memories. Unless they are quite small, take what you catch.
Keep us informed.
Ken