Raw Prime Fish Meat is acquired by harvesting the larger and more exotic fish in Ark Survival Evolved. It can also be harvested in smaller quantities from common fish of high level. It spoils more slowly than Raw Prime Meat.
Fishing is the best way to get this less common type of raw fish meat. While it can be acquired by haresting nearly any fish you'll get far more from using a fishing rod. While it spoils faster than regular Raw Fish Meat you'll find that you get more food value from Cooked Prime Fish Meat than you will from Cooked Fish Meat.