Combine first 3 ingredients in a small bowl, stirring well with a whisk.
Sprinkle fish with salt and black pepper.Thread fish, bell pepper, pineapple, and onion alternately onto 8 (8-inch) metal skewers. Place kebabs in a shallow dish; add marinade. Cover and chill 30 minutes.
Remove kebabs from dish, reserving marinade. Place marinade in a small saucepan, and bring to a boil; remove from heat. Place kebabs on grill rack coated with cooking spray. Grill 10 minutes or until fish flakes easily when tested with a fork, turning kebabs occasionally and basting with reserved marinade.