1. Beat butter at medium speed with an electric mixer until creamy; beat in powdered sugar until smooth. Stir in vanilla extract.
2. Combine flour and salt in a medium bowl; beat into butter mixture. Stir in mini morsels. Flatten dough into a disk, wrap in plastic wrap, and chill 1 hour or until firm.
3. Preheat oven to 350°. Line 2 baking sheets with parchment paper.
4. Roll dough to 1/4-inch thickness on a lightly floured surface. Cut out shapes with a 4-inch fish-shaped cutter. Place on prepared baking sheets. Bake 8 to 10 minutes. Place large morsels on cookies to resemble fish eyes. Cool on pan 10 minutes, and transfer to wire racks to cool completely.