Clean and gut fish leaving head on. Rub inside and out with salt. Mix bread cubes, onion, celery, salt, 1/4 c butter, and just enough water to moisten. Toss lightly. Stuff fish with dressing. Melt 1/4 lb. butter and add lemon juice. Pour over fish and dressing. Drugstore wrap (moisture tight) in heavy duty foil. Bake on a cookie sheet at 350 F for 3 1/2 hours