A big swordfish is an abnormally large raw swordfish caught while fishing at any cage/harpoon fishing spot, it is obtainable by both barbarian fishing and by normally fishing swordfish using a harpoon. Since players can only get it while fishing for swordfish, it requires 50 Fishing to obtain. It is a very rare catch (1/2500).
Previously, if a player attempted to cook a big swordfish they would get the message "You don't have any more swordfish to cook." Now, players can cook big swordfish just like normal swordfish (the player will receive the normal XP and will receive a cooked swordfish, if they don't burn it).
Whenever you catch a big swordfish you will receive the message: "You catch an enormous swordfish!"