LOL. Thank you guys...
I wasn't sure because "Kashrut" which are the Jewish Laws of food make it so we cnnot eat some types of fish.
Kosher fish are identified by their scales. Obviously, crustaceans (such as lobster) and other shellfish (such as clams) are not Kosher because they lack scales. All "scales" however, are not Halachikally equal. Halacha defines a fish scale as a growth on the side of a fish similar to a fingernail – it must be removable without damage to the skin of the fish. Sturgeon, although it has primitive bony plates on its sides, is not considered Kosher because the scales cannot be removed without damaging the flesh. Sharks are similarly not Kosher, because their skin is covered with tiny teeth-like armor, which are not considered scales at all. The first step in determining a Kosher fish is verifying that it has a Kosher scale. Although many Kosher fish are completely covered with scales, Halacha requires only a minimum number of scales to accord a fish Kosher status (see Y.D. 83:1). Tuna, for example, have very few scales, yet are nevertheless considered a Kosher fish.