When comparing the nutrition content of the same size of fillets and the fresh form of the fish, both are low in mercury. However, codfish is healthier, although Alaskan pollock is mercury safe. Not only does cod have more protein and lower cholesterol, but more thiamin, iron, niacin, folate, potassium, phosphorus, zinc, and calium. It tastes sweeter, while the meat is firmer and holds together better during cooking.