Corroborated
Tuna
A major boss-tier catch on Island 4: both a high-value fish and the item used to summon Albatross.
How to Find It
Caught with a Professional Boss Lure, then placed on the ground as bait to summon Albatross.
Rewards
Reported value of 2,000, far above any normal-tier fish.
Two independent fish-list sources (Game8, Destructoid) both list Tuna in their boss tables, resolving earlier uncertainty about whether Tuna was just a fish or also a boss encounter. It appears to be both: a prized catch that then becomes a boss-summon item for Albatross. See also the `fish/tuna` entity for its role purely as a catch.
Related
Albatross
The Island 4 boss: a bird-type creature summoned by placing a caught Tuna on the ground as bait. Its exact name is disputed across sources.
Island 4
The fourth island. Home to the Tuna boss/catch and the disputed Albatross bird boss.
Professional Boss Lure
Boss bait used to catch Tuna, a major Island 4 boss/catch.
Tuna
A major, high-value catch on Island 4, caught with a Professional Boss Lure, then used as bait to summon the Albatross boss.