A big swordfish is an abnormally large 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).
To stuff the big swordfish, players must take it to the Taxidermist in Canifis. She will charge the player 2,500 coins and turn it into a stuffed swordfish. Once it is stuffed, players can mount it in their Skill Hall at 56 Construction, using a stuffed swordfish and 2 teak planks, producing a mounted swordfish.