Heat oil in large nonstick skillet over medium-high heat.
Sprinkle fish with salt and pepper; dust both sides with flour. Add to skillet; cook until browned and just opaque in center, about 2 minutes per side.
Transfer fish to platter. Add grapes, wine, and butter to same skillet. Bring mixture to boil, whisking up any browned bits. Add capers and parsley. Simmer sauce until slightly thickened, about 3 minutes. Season to taste with salt and pepper. Spoon sauce over fish.