Saute celery, onion, parsley, shallots, green pepper, and garlic in butter in a large skillet over medium heat; cook until vegetables are tender.
Add flour, and cook 1 minute, stirring constantly.
Gradually add milk and wine; cook over medium heat, stirring constantly, until mixture is slightly thickened.
Remove from heat; stir in crabmeat, bread crumbs, salt, and pepper.
Place 6 fillet halves in a greased jelly roll pan; spoon about 1/2 cup crabmeat stuffing on each fillet.
Cut remaining fillet halves in half lengthwise; place a fillet fourth on each side of stuffed fillets in jellyroll pan, pressing gently into stuffing mixture.
Top each portion with Mornay Sauce; sprinkle with paprika.
Bake at 425° for 15 to 20 minutes or until fish flakes easily when tested with a fork.
Garnish with parsley, if desired.