Heat oil in a large nonstick skillet over medium-high heat until hot. Add onion, green bell pepper, and garlic; sauté until tender.
Add tomatoes and next 6 ingredients. Bring to a boil; add fillets, spooning tomato mixture over fish. Reduce heat; cover and simmer 12 minutes or until fish flakes easily when tested with a fork.
Garnish with basil sprigs, if desired, and serve immediately.