I Have been making this for a couple of years now. But never had used it on catfish. I did do so Wed nite when I fried some of the catfish I caught Sat. Had guests in and they thought it was the best ever.
Make sure fish is dried off well. And this will all depend on the amount of fish or whatever you are frying.
For exanple
1 cup of Bisquick mix
1 cup of cornstartch
and enough beer to make a batter to barely hang onto a fork
about 2 tsp of vanilla and a some onion powder.
Leave stand for a few hrs so the beer gets stale.
Drink whatever is left over of the beer
or you can open the beer and let it stand to become stale, whatever is left over can be put in a closed container and refrigerated for another time.
My fish were good sized fillets so I cut cross wise in strips of about 1 1/2 in wide. make a good finger food.