Giant Squid can be obtained at level 100 Fishing.
This fish can be acquired by casting a fishing rod into bodies of water that indicate a 
Bass to fish at this fishing spot. Upon being caught, it gives you 55,000 exp in the Fishing skill.
Location
You can obtain Giant Squid by Fishing at the Docks south of Brightleaf Forest, and inside Mushroom Island.
Recipe
| Skill level | Item | Materials | XP | Merchant Price |
|---|---|---|---|---|
| 100 Cooking |  Cooked Giant Squid |
1x Giant Squid 1x Black Salt |
41,500 | 3,000 |