Preheat the oven to 375F. Line a baking sheet with parchment paper. Add fillets to the baking sheet. In a small bowl, mix together 1 tablespoon oil, cumin, 1 teaspoon salt, turmeric, and pepper. Drizzle the mixture over the fillets, then use your hands to rub it all over each fillet. Bake for 10 minutes, or until cooked through and flakes easily (this will vary a lot depending on which fish you use/how thick it is).
In a medium bowl, add the fennel, 1 tablespoon oil, lime juice, and ¼ teaspoon salt and toss to coat. Transfer to a serving platter or large plate and top with the orange and avocado. Sprinkle the remaining ¼ teaspoon salt all over the avocado and citrus. Drizzle with remaining 1 tablespoon olive oil. Top with black pepper and fennel fronds (the hairy green tops of the fennel).
Serve the fish with the salad. To bulk it up, add some crusty bread, roasted potatoes, or rice.