Preheat oven to 400º. Line 9×13” baking dish with foil.
Place 4 slices of bacon in baking dish; top with fillets. Place 1/4 of onion slices over walleye. Drizzle with melted butter & honey. Sprinkle with salt & pepper. Cover pan with foil; bake until fish flakes easily with a fork, 12-15 min.
Meanwhile, cut rest of bacon slices and place in skillet with remainder of onion. Cook & stir over med. heat until the onion is soft and translucent, about 5 min. Reduce heat to med-low; continue cooking & stirring until onion is tender and golden brown, and bacon is crisp, about 15