Flathead patrol crappie structure, fallen trees are a favorite hangout for them that's laying down in the water and cement structure like below dams they patrol along the cement walls looking for crappie... If you know where there's trees laying under the surface that can't be seen above the surface usually always has a flathead hanging out on it... Here's how I target flathead out in the lake.. I usually have sunken trees marked on my gps prior to fishing for them but on these trees I'll have to sneak up on them with either the wind drifting me towards the tree or trolling motor to get me close to it on the downwind side of it is best ... if using the wind I let the wind carry me over it until I"m on the downwind side making sure all my bilge pumps are off ... even my aerator on my bait tank so that I won't spook them and I'll get about 30 yards away and I'll take a live bluegill and scale it on both sides and put the hook through the back behind the dorsil fin with my float rig ... don't want to hook them in front because they'll be swimming towards the mainline and get it all tangled up ... if they're hooked behind the dorsil they'll be swimming away from the mainline and sinker drop so they don't get tangled up and I usually use at least a foot long dropper loop .. if I rig a rig up for flathead then I"ll use a 3 ft leader with swivel on the mainline stopped about 2 ft above the sinker so that they can swim around fairly freely as this attracts the flathead even more ... when you scale your baits the flathead home in on them a lot faster because they mimic a bait that's been previously hit by a channelcat as channels and blues love bluegill but lots of times they get away from them but lose lots of their scales and even bruise their meat up so they're easier for the flathead to catch ... I think the flathead have evolved to know this and they send out some kind of fluid scent when their scales are removed because when fishing below the dam all those years I learned that .. this is also how I started my boys out fishing was to have them flathead fish while I fished for blues because they didn't have to cast very far to fish for flats. Friend of mine was below the dam fishing all day when we arrived and said he hadn't gotten a bite all day and I asked if he was scaling his baits becuase he was flathead fishing ... he said no so I had him raise his bait up and I scaled it for him and before I got back to the steps where my rods were to rig them up he caught one ... he'd been fishing for about 6 hours without a bite and after scaling the bait he had one within 5 minutes ... he caught 3 more within about an hour and packed up and left but that's how much difference the scaled baits make. Fish around flathead structure with scaled baits and you'll do well. crappie is probably a flathead's favorite food fish but might be illegal to use in texas ... they're legal to use here if you catch them legally on rod n reel but bluegill and green sunfish work well too... in the fall bullhead, small channels and small blues work good for flahead bait too
listen to to tiny, you'll not only catch flathead but will catch bigger fish in general... I scale my gizzard shad,...you have probably as much chance catching big flathead by fishing for crappies or white bass (they sure posted a lot of flathead pics)...my experience with big fish, be it blues, hybrids or strippers, came when there were min man made sounds... I RnR from the bank, and only caught a few flathead biggest 15 lb, but I'm quite sure big fish live long because they learn to stay away from human.