Heat the broiler (grill). Position the rack 4 inches from the heat source. Lightly coat a baking dish with cooking spray. Place the fish on the prepared baking dish. Squeeze the juice from 2 lemon wedges over the fillets. Sprinkle with thyme.
Broil (grill) until the fish is opaque throughout when tested with the tip of a knife, about 8 to 10 minutes. Remove from the oven. Serve immediately, garnished with the remaining two lemon wedges.