From In-Fisherman Mag..

Deep Frying Rules
* Any wet batter must be ice cold, so that when it hits the hot oil it instantly seals the batter around the fish, allowing the fish to cook by steaming within the firm crunchy crust. The fish doesn't get soft and the batter doesn't get soggy.

* To seal batter properly around the fish the oil must range from 360F to 380F. Without a thermometer you can tell if the oil's ready by adding a drop of the batter to the oil. The batter will bubble profusely on the surface if the temperature's right. If the batter's too warm or the oil's not hot enough, the batter just sits there, barely bubbling while getting soggy.

* Don't add so much fish at once that the oil temperature drops too low. Allow the oil to heat back up between batches of fish.

A Nice Dry Breading
Flour seasoned with salt and pepper
A pinch of cayenne
Perhaps dry herbs, and garlic salt
Several beaten eggs with a little milk
Corn meal (or cornflake crumbs)
Dip a small fillet (or fish portion) in the seasoned flour, then in the egg mix. Allow the excess egg to drip off, then dip the fillet in the corn meal. Deep fry.

A Nice Wet Batter
1 egg yolk
1/2 c. ice water
3/4 c. seasoned flour
Mix the egg yolk, water, and flour. Dip a fillet, let the excess batter run off. Deep fry.

Good Fishing,
Gary