PREHEAT oven to 400°F. Cut opened pkg. of fish into 4 equal pieces.
MIX zucchini and 1 cup of the salsa in 9-inch square baking dish; top with fish. Spoon 1 Tbsp. of the remaining salsa over each piece of fish.
BAKE 15 min.; sprinkle evenly with cheese. Bake an additional 8 to 12 min. or until fish flakes easily with fork.