Pangasius (Wikipedia) says:
Pangasius is a genus of medium-large to very large shark catfishes native to fresh water in South and Southeast Asia.
In 2011, Pangasius was sixth in the National Fisheries Institute’s "Top 10" list of the most consumed seafood in the United States.
If I understand correctly, fresh water is not sea water, and has little salt.
So why can a fish living in fresh water be called seafood?