In a small bowl, combine sugar and cornstarch. Stir in the vinegar, water, soy sauce and hot pepper sauce until smooth; set aside.
In a small resealable plastic bag, combine the flour, salt and pepper. Add fish and shake to coat. In a small skillet, saute fish in oil for 4-6 minutes or until fish flakes easily with a fork; remove and keep warm.
In same skillet, saute green pepper and onion for 3 minutes or until crisp-tender. Add pineapple. Stir sauce and add to skillet. Bring to a boil; cook and stir for 2 minutes or until thickened. Return fish to skillet; heat through. Serve with rice.