call it the 3-2-1- parts mixture.

3 parts Italian bread crumb
2parts buttermilk pancake flour
1 part corn starch for the sticker

mix all ingredients into a large plastic ice cream bucket, I do this because I freeze whatever isn't used up for more applications later on.
Its up to you how much you make up for future usages.
Into that mixture I will add seasoning salt and cayene pepper to taste, this is very important you don't over do it.

Step one you put the fillets into that ice cream bucket and shake until fully coated.
Step 2: I make an egg/milk wash and add tobasco and lemon juice(not too much) to bam that wash up, dip your fillets into that wash and
Step 3: then dip the floured washed fillets into panko bread crumbs

put your fillets on a cookie tray/cover with tinfoil etc. and refrigerate for a few hrs, I've done them over night also, it adheres all the ingredients much better into the panko.
Lastly, get some peanut oil, its the best for cooking fish bar none! It has a nice high cooking point, way better than vegetable oil or canola oil which comes from the rapeseed family of which they make mustard gas with, so you do the math, Cook at 325-350. Your taste buds will be over joyed.

fwiw, I even use the flour mixture on freshly cut potatoes for frying, very good indeed.