Rinse fish and remove any bones.
Mince fish and shrimp, then transfer to a large bowl.
Stir in 1 cup of bread crumbs, 1 egg, cilantro, lemon juice, salt and pepper. Mix well and form into 24 balls.
Roll balls in remaining egg, then in remaining bread crumbs to coat completely.
Cover and refrigerate 30 minutes.
Heat 2 tablespoons oil in a heavy saucepan, add onion and cook, stirring, 5 minutes to soften.
Add chilies, garlic and turmeric; cook 2 minutes more.
Stir in coconut milk and tomatoes and cook , uncovered 20 minutes, until reduced and thickened, stirring occasionally.
Half-fill a deep pan or deep-fryer with oil and heat to 375f (190c), or until a 1-inch bread cube browns in 50 seconds.
Fry fish balls 3 to 5 minutes, until golden brown.
Drain on paper towels and serve with the sauce.