I find that reds, black drum, and other large-scaled fish are very difficult to fillet, because even a very sharp fillet knife (including bigger knives like Bubba blades, etc) tend to slip off the scales rather than cutting down into the meat. I usually just try to work the blade under the scales and up towards the head and then cut down, but I was wondering if there was some other trick that people used for them. I've had too many nicks and close calls with blades skidding off large-scaled fish to keep at that routine.

Scale them first.

Big Norm's Magic Fish Scaler

I use electric American angler with the thick blades. The saltwater unit with stainless gears goes through big slot reds pretty easy.

I also use the orange American Angler, but get the scales out of the way on the bigger fish first. The Big Norm's Fish Scaler will scale a 30 lb carp w/ ease. It is pretty amazing. It also makes a great gift idea since it is so cheap.

I always wear a cut proof glove on my fish holding hand. Unless I'm cleaning everyone's fish, I find it to be faster and with less prep and subsequent cleanup later just using a sharpened Rapala filet knife over an electric knife. I never have scaled one. Might be a good option. Everyone has their own way of doing things. I've cleaned a lot of reds side by side with other folks and haven't witnessed anyone doing it better or easier or faster.

First cut I make is right behind the pectoral fin. I don't cut straight down, the scales are too tough. I angle my blade at about a 45 towards the head after working it under some of the scales. So you are inserting your blade against the grain as if you were going to scale the fish with the knife. Too many people try to saw through the heavy scales with shear horse power. That works okay with an electric knife but not a manual knife.

After the initial cut is made as deep as you can go, I work the blade tip up behind the head to the top just in front of the dorsal fin. I cut deep here until I get to the bones coming up off the spine. Those bones will guide your blade as you cut towards the tail. At this point, I've cut from stem to stern to about the rib cage and the center of the spine. I let the ribs guide my knife again as I cut towards the belly. Your off hand is applying gentle lifting pressure all the time as you cut. That's pretty much it. Repeat on side two. If there is a lot of effort and brute force necessary, your knife may be dull or the cut is in the wrong place or at the wrong angle. Once the initial cut is made (and that shouldn't require any sawing or extreme effort) the scales shouldn't really come into play.

If you are doing half shell, your done except for the rinse. You can get meat off the throats, back bone, or make a stock with the scraps and head. Maybe when I'm retired.

that last post seems wasteful and awkward
maybe this

https://www.youtube.com/watch?v=DlwfKBsgImg

saws all for big drum. also good on deer and hogs.