Melt 2 tablespoons of butter in a large frying pan over medium heat.Dip each fish in milk, then in flour; season with salt and pepper.Carefully ease fish into pan and fry over medium heat for about 3 minutes per side.Transfer fillets to a warmed platter.Melt remaining butter in a small skillet; add capers and quickly heat through. Pour over fish, squeese lemon over dish and serve immediately.