Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Dice the zucchini and red bell pepper into bite-sized pieces and mince the garlic cloves.
Place the zucchini, bell peppers, and cherry tomatoes on the baking sheet, then toss with 1 tablespoon of olive oil, half the oregano, and half the salt and pepper.
Spread the vegetables in a single layer and roast for 10 minutes until they begin to soften.
While the vegetables roast, pat the cod fillets dry with a paper towel and season both sides with the remaining olive oil, oregano, salt, pepper, and minced garlic.
Remove the baking sheet from the oven, move the vegetables to the outer edges, and place the cod fillets in the center.
Return the pan to the oven and roast for an additional 10 to 12 minutes until the cod is opaque and flakes easily with a fork.
Remove from the oven, drizzle the fish and vegetables with fresh lemon juice, and garnish with chopped parsley before serving.