Sift flour and salt into bowl. Beat eggs with butter and add to flour mixture. Add milk gradually, stirring only to mix. Add more milk if batter is too stiff. Cover, allow to stand 3 hours.
Meanwhile, soak catfish in cold water. Drain, remove bones and skin. Pound fish in mortar with hot pepper. Add scallions, garlic, parsley, thyme and allspice. Stir into batter and let stand 30 minutes.
Heat oil in deep fryer to 375°F and fry mixture by heaping tablespoons until golden brown. Drain on paper towels and keep warm.