What bait? What depth? What rig? I wanna try to catch one in canyon lake or the quadalupe river this weekend. Please help

I can only really answer the bait question. Live perch around 4" long. Green sunfish if you can get them.
For the rest, not sure but a 3/4 or 1 oz egg sinker on top of a swivel with an 18" leader and a 2x strong treble hook through the nostrils of the perch might work. Not sure on depth but you might try drifting at different depths.
Good luck and hope you get you one.

Old flathead post

if your asking specifically how to catch one on R&R then I assume you maybe have already caught them on trotlines/juglines/etc. the fish are where the fish are.....go to the same spots, use the same baits....just hang them on big fishing rods and wait.

Always had good luck with a 3 way swivel. 50# mono main leader for the perch about 12-15 inches long, then a 5 inch 10# mono leader tied to a 2 or 3 ounce weight. This will allow the perch to swim off the bottom but not pull the weight around. Also the lighter line tied to the weight will allow it to snap off should it snag on something while you are reeling in. Have caught many yellows with this rig using 20# big game as your main line. Biggest went 52 pounds, heck of a fight on a rod and reel. Good luck

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.

Just go striper fishing with Randy Wood

seen alot hit a slab at 30 feet fishin for sandbass. I caught one one time drifting with fresh dead shad, I had glow beads on my line, pretty hard to catch appaloosa except 1 week out of the year they go crazy you will see every year in october they get caught kind of seasonal in my experience! next one I catch im gonna eat it !

If I was going to fish my brush piles for flatheads,
Circle or j hook ?
Free spool with clicker or drag locked down ?
Over the top of the pile or on bottom around the edge ?


Thanks.
Mo

Tiny is the man! Listen to what he says

I have caught several on jigs when bass fishing but I am sure that is not a good way to target them.

Caught big ones when fishing live bluegills under a float near weedlines at night while again targeting bass.

Never tried scaling the gills but sounds like a great tip; if I were to target them I would for sure give it try based on the comments here.

Good luck!

For this part of the world try to catch some nice sized Rio grandes they can smell them better I think. Or scale the bull shad from the river like tiny said.

Tiny, what are your rates? Really want to learn!