Raw Fish Meat is easily acquired by harvesting Fish in Ark Survival Evolved. The use of a Fishing Rod greatly increases the amounts that you will receive.
The easiest way to harvest Fish Meat is by spear fishing. This however is not the best way to get good quantities of Raw Fish Meat. By using a Fishing Rod you can get much more meat per fish.
Raw Fish Meat spoils much more slowly than regular Raw Meat but Cooked Fish Meat does not provide as much food value as Cooked Meat. The quantities you get from Fishing and the fact it spoils much more slowly can easily offset this however.