Prepare the Chermoula: In a mixing bowl, combine garlic, parsley, cilantro, cumin, paprika, turmeric, lemon juice, and olive oil. Mix until well-blended. Add salt and pepper to taste.
Marinate the Fish: Place the fish fillets in the chermoula, coating them well. Allow them to marinate for 20-30 minutes.
Prepare the Tagine Pot: Layer the bottom with sliced red and green bell peppers and tomatoes.
Add Fish and Cook: Place the marinated fish on top of the vegetables in the tagine pot. Cover and cook on low heat for 30-40 minutes, or until the fish is tender and flaky.
Serve: Garnish with fresh herbs and a squeeze of lemon, and serve with couscous or crusty bread.