How many bosses are in How to Fish?
Community story route: Spider Crab, Giant Piranha, Pufferfish, Albatross, Bowhead Whale, then Mutated Bowhead Whale. Mini-bosses (Sunfish, Old Pike, Blue Shark, Tuna, Goblin Shark) use boss lures and are optional for story. Not first-party.
How do I summon the Pufferfish?
Catch a Needlefish on the Standard Lure, give it to the Desert tourist, use carrot bait. Officially nerfed in Patch 1.0.4.
How do I fight the Albatross?
Catch a Tuna with the Professional Boss Lure, drop the body on the ground, do not sell it. The bird is attracted to tuna — not hooked on a rod (KeenGamer, GrindnStrat).
How do I beat the whale?
Fish Bucket → Bowhead Whale, then use the whale body at the volcano for Mutated Bowhead Whale. Both whales were nerfed in Patch 1.0.4. Ending boat notes are community-sourced.