Mix paprika, coriander, cumin, cinnamon, and cayenne in a small bowl. Heat oil in a large skillet over medium heat. Add paprika mixture and garlic and cook, stirring constantly, until fragrant, about 30 seconds.
Add tomato paste and cook, stirring constantly, until darkened, about 1 minute.
Stir in spinach, 1 1/2 cups water, sugar, salt, and several grinds of pepper; cover and bring to a simmer over medium-high heat. Cook, stirring occasionally, 3 to 4 minutes.
Nestle fish in sauce and return to a simmer. Reduce heat to medium and cook, covered, until fish is cooked through and flakes easily with a fork, 5 to 10 minutes depending on thickness.
