COOK rice as directed on package. Meanwhile, combine mangos, cucumbers, onions and 1 Tbsp. dressing.
HEAT oil and remaining dressing in large nonstick skillet on medium-high heat about 10 min. before rice is done. Add fish; cook 3 min. on each side or until fish is browned on both sides and flakes easily with fork.
SERVE fish with rice and mango salsa.