Preheat the oven to 425°F. Lightly grease or spray a baking tray. Once the oven is fully heated, place the baking tray inside to heat up—this helps achieve crispy skin.
In a small bowl, mix the melted butter with lemon, lime, and orange zest, minced garlic, and crushed red pepper.
Wash and pat dry the salmon fillets, then carefully place them skin-side down on the hot baking tray. Sprinkle with salt and black pepper.
Evenly spread the seasoned butter over the salmon, reserving 1 tablespoon for later.
Bake for 14–18 minutes, or until the salmon is cooked through.
Remove from the oven and spread the reserved tablespoon of butter over the top before serving.