Cavefish

The Cavefish is a type of fish that players can only find in the Living Rock Caverns underneath the Dwarven Mine. Players who wish to catch Cavefish should beware of the high level Living Rock Guardians in the area. They were introduced with the Living Rock Caverns update on 17 September 2009. They heal 20 hitpoints (up to your max hitpoints) and boosts a random combat skill by 2 points (excluding summoning). Cavefish, like all other fish, are consumed in one bite.

Players need 85 Fishing to catch cavefish, and 88 Cooking to cook them. Fishing Cavefish yields 300 experience, while cooking yields 214 experience. Players wearing cooking gauntlets will stop burning Cavefish at level 95 Cooking.

You need a fishing rod and normal fishing bait to catch cave fish