Raw Stripefish require level 15 Fishing and a Fishing Rod to catch. Each fish rewards 83 fishing experience.
Requiring level 15 Cooking, Raw Stripefish can be cooked into Stripefish, rewarding 83 cooking experience.
As shown by the red outline in the picture of the map below, players can fish Raw Stripefish west of Lighthouse. However, a boat is required to reach this location. Furthermore, as a leveling tip, the blue outline shows a location where players can fish two spots without having to move, increasing experience per hour.
[Accurate as at 06/09/2018] Leveling from 15-25 (where level 15 is the earliest players can catch Raw Stripefish, and where level 25 is the next tier of fish, Sarkas) requires a total of 84,802 experience (level 25: 101,186 - level 15: 16,384). Because each Raw Stripefish rewards 83 Fishing experience, a player has to catch 1022 Raw Stripefish in order to reach level 25 (84,802 / 83).