cfal,

Do you know anything about the pond's history? For example, are the brown bullhead all that remain of a more diverse stocking? May be worth investigating. They look big enough to eat and so you may be able manage them by hook and line. Were I doing that, I would consider harvesting a slot between 8 and 10 inches to ensure the largest fish could serve predation.

If you find the pond may have winter killed before then it may be better to avoid fish that need higher DO. Esox sp. as a bonus in limited quantity may be an option that could survive events that would kill Centrarchids for example.

Anyways, its hard to kill out bullheads which can survive in mud for a time. Might take rotenone. But if you like the bullheads and they are achieving harvestable sizes, I would consider only introducing predators on a limited basis as bonus fish. There may be enough predation by the larger Bullheads to achieve harvest sized fish on an on going basis. A pond like that could carry 400 lbs or more of BH and so consider starting with a goal of 80 lbs/year using a slot as the harvest size.