Combine catsup, lemonade, garlic, bay leaves, salt, pepper, and mustard in a large shallow container, stir well.
Add fillets; cover and chill 1 hour.
Drain fillets, reserving marinade.
Place fillets in a fish basket coated with cooking spray.
Grill fish over hot coals 6 to 8 minutes on each side or until fish flakes easily when tested with a fork, basting often with reserved marinade.
Remove bay leaves before serving.