Preheat oven to 400°F and line a large sheet pan with parchment paper.
In a small bowl, combine paprika, garlic powder, onion powder, cayenne pepper, thyme, ½ tsp salt, and ¼ tsp black pepper.
Toss the zucchini, squash, and bell pepper with 2 tbsp olive oil, remaining salt and pepper. Spread on one side of the sheet pan.
Pat the tilapia fillets dry and brush both sides with remaining 1 tbsp olive oil. Generously coat both sides with the blackening spice mixture.
Place the seasoned tilapia on the other side of the sheet pan. Bake for 12-15 minutes, or until the fish flakes easily with a fork and vegetables are tender.
Serve immediately with lemon wedges for squeezing over the fish. Perfect over rice or quinoa!