preheat oven to 400

melt butter in a small skillet over med. heat, add garlic and saute 1 mim. Add breadcrumbs, tarragon, lemon rind, salt & pepper. Stir well.

Place halibut on a parchment-lined baking sheet. Combine mayonnaise and horseradish; spread over each fillet. Top with crumbs, patting lightly to help them adhere. Bake 10-12 min, or until fish is tender and crumbs are golden.