Preheat oven to 375°F; pat dry tilapia filets and season with salt and pepper; place tilapia in a baking dish coated with cooking spray or lined with foil; set aside
Melt butter in a small skillet over medium heat; cook the celery, onion and garlic in skillet until tender.
Stir in flour and thyme; gradually whisk in milk; bring to a bubbly boil; stir in the lemon juice and hot sauce.
Remove skillet from heat; stir in mayonnaise, crab and bread crumbs; spoon onto tilapia filets.
Bake tilapia, covered, ~15 minutes; uncover and bake ~10 minutes more, until fish flakes easily with a fork.
Nutrition Facts: Servings: 8; Amount per serving: Calories 141; Total fat 4.7g 7.2%; Saturated fat 2.9g 14.5%; Cholesterol 13mg 4.3%; Sodium 189mg 7.9%; Carbohydrates 22.4g 7.5%; Fiber 1.5g 10.7%; Sugars 1.1g 2.2%; Protein 3.3g 6.6%; Based on DV of 2000 calories per day