1. Preheat oven to 400 degrees Fahrenheit.
2. Cut fish into 12 slices. Cut each slice in half.
3. Place one piece onto each square.
4. Lightly moisten edges of pastry with water. Fold dough over fish, forming a triangle. With tines of a fork, press around edges to seal.
5. Bake for 20–25 minutes or until golden brown.