and i have no clue what the flatheads do but if your having a hard time getting bedded fish to bite .... if you can see them keep casting to them they will get mad and bite the bait to move it outa there nest ... also if you can find a bait that is a known flat head egg eater or flathead fry eater then i'd try using that its sure to piss them off and make them bite out of fear or anger or danger to the young .
with most fish tempature plays an important role in the spawn procedure as well as water conditions and if there tails are all bloody then there prolly half way or more threw spawn. are you catching any with big heads and no bellys? evadence of females that droped there eggs already the bloody tail is from / fanning the tail to clear momma out a bed / circulate water on the eggs and spreading the baby batter ... now you gota find out do the parents deliver the young and leave them like most channel cats or do they guard them un till there a better size and can defend there self .
and you found the best cat fishing website in the world these people are great and very friendly and will for the most part share info and tips and if your really lucky ,
meet some one like matt77 who will forget to hog tie you and blind fold ya befor they reveal there honey hole or BIG CAT HEAVEN to you welcome and sorry i couldn't give ya a better answer