Our understanding of the nutrient contribution of fish to human diets relies on nutrient composition data for a starkly limited number of fish species. Yet particularly for the most nutritionally vulnerable fish consumers around the world, fish consumption includes a wide diversity of fish species whose nutrient composition data is disparate, poorly compiled, or unknown. To address the gap in understanding fish nutrient composition data, we reviewed the literature with an emphasis on small indigenous species of fish that are missing from global databases.