whenever you use a wet batter it helps a great deal to dredge the moistend filets(moisten with water lemon juice or what ever but not dripping wet)first in seasoned flour to give the wet batter something to stick to. Like some of the others have said hold the filet in the oil for a second or two before dropping in the "HOT" oil. Again like others have said make sure your oil is hot 350 to 365 will do and dont over crowd the vessel you are cookong in. Please do not test your oil with water sooner or later you will regret it. A small pinch of flour or a drop of your batter will tell you if its hot enough. You should see the flour sizzle or the batter form a ball and sizzle immediately.