I moved my 10gal tank from my room to the garage during late spring time. I had two black bullheads, one yellow, one brown and one black x brown bullhead. I noticed four bullheads were in same corner of tank while a big black bullhead on opposite side of tank. And there was 15-20 black fry in the pipe which big black was in. I believe that big black was father and i have no idea whos mother as all four bullhead were rugged and beat up from the overprotective father.
I give the fry away to my LFS, the public schools, the bait stores (they have aquariums) and my friends whose has big tank and pond. I gave all five bigger bullheads to my friend has private pond with farm sunfish and LMB.
I kept one fry and it turn out as great awesome looking bullhead with beautiful mottled patterns on its body. And it appeared its body were slender, just like yellow so its possible that its black x yellow or its possible black x brown because of markings. But its not pure black bullhead. Sadly this beautiful bullhead passed away due to my newbie errors. (at last he reached 11 inch long in 3 years)....and that was long time ago. Now i will never do that again as i know whats my limits.
And i thought bullheads need to be big for spawning but i was wrong as theres stunted bullheads reproducing in small ponds and lakes just like stunted LMB, sunnies, perch and crappies.