The USDA’s FoodData Central website provides health facts for seafood, among other products.
There are 2600 entries for fish, 154 for shrimp, 95 for shellfish, 9 for cephalopods. More fish can be searched by common/market name such as pangasius, albacore, etc.
To view, click the link and search using the field on the left side of the website: https://ndb.nal.usda.gov/fdc-app.html#/food-search