It is necessarily true of all foods as phosphorus is an important component of proteins, DNA, RNA and phospholipids, among many other biomolecules that are present in all living organisms that later become fish foods. Certain fresh, frozen and canned seafoods from the grocery store also can have added phosphate that helps keep moisture in the seafood so it looks fresher.
As to which foods have more or less phosphate, I know the answer for many foods that people eat, but not so much for fish foods, where one would need to relate it back to the amount of nutrients of various sorts also present, like the protein to phosphorus ratio, etc. I've not seen that sort of info.