Preheat the oven to 180 degrees Celsius and prepare a large baking dish. Rinse the fennel bulb and zucchini. Remove the bottom and tough core from the fennel and cut the rest into thin strips. Cut the zucchini into equal, not-too-thick slices.
Distribute the cut fennel and zucchini evenly over the bottom of the baking dish. Place the 150g fresh salmon fillet in the center on top of the vegetables. Then lay the lemon slices on the salmon so the flavor infuses into the fish as it bakes.
Slide the baking dish into the center of the hot oven. Bake the dish for fifteen to twenty minutes. Check after a quarter hour if the salmon is done. The fish is ready when it's light pink inside and opaque, and the flesh flakes apart easily.
Remove the baking dish from the oven and let the dish rest for a minute. Scoop the softened fennel and zucchini onto a plate and place the warm salmon fillet with the lemon slices directly on top.