They require a Cooking level of at least 90 to cook and give 215 Cooking experience per fish. It is advised to always cook raw dark crabs with Cooking gauntlets equipped due to their high burn rate, as they are still possible to burn even at 99 Cooking (and with the +5 boost from Chef's Delight). Wearing a Cooking skill cape, however, will ensure 100% cook-success rate due to its perk.
Completion of the Wilderness Elite diary will reward the player with a higher success rate when trying to catch raw dark crabs.
There are only two locations at which dark crabs can be caught:
Wilderness: North-eastern coast, south of the fence containing the deep Wilderness.