How to Fish Pufferfish — The Desert Island Gate
It rolls in a straight line. Open ground kills you; a tree line saves you.
The Pufferfish is the third story boss in How to Fish and the gate that opens Island 4. It is the first fight decided almost entirely by terrain rather than gear. The boss moves in slow, committed straight lines, which means a player with the cheapest workable gun and good angles beats a player with an expensive gun standing in the open.
Patch 1.0.4 nerfed its health, so it is no longer the spike it was at launch. What it still does is punish players who back away in a straight line and get flattened, or who cross behind it at half health and walk into poison.
Get the Carrot
The trigger is the Carrot, and it comes from the tourist sitting under the tree on the Desert island. He will not accept an ordinary catch. He wants an endangered creature — a Needlefish is the usual answer — so fish the island pools until you land one, then hand it over. He gives you the Carrot in exchange.
Equip the Carrot as bait and cast. Nothing in the shop replaces it: the Standard Boss Lure summons the Blue Shark, which is the kill that unlocks the grill and is well worth doing first, but it will never spawn the Pufferfish. Which lure pulls which pool is listed in Lures & Bait.
Do the Blue Shark before the Pufferfish if you can afford the lure. Talking to the NPC beside the grill after that kill gives you the lighter, and from that point cooked food both heals more and sells at 1.5x, which changes every fight after it. See Cooking & Grill.
Fight it on your terms
The Pufferfish rolls. It picks a line, commits to it, and travels slowly along it. That predictability is the whole fight. Stand in open sand and it simply runs you down; fight near the tree line and every roll ends with the boss stuck resetting its angle while you shoot.
The working loop is short. Put two shotgun shells into it, then immediately run to the opposite side so it has to turn and start a fresh approach. Shoot again from the new angle. Keep relocating before it can pin you against a rock or a hut wall. Never let a roll line up with a dead end behind you.
At roughly half health it grows and starts trailing poison behind itself. This is where most attempts die, because the instinct is to chase and cut the corner behind the boss — directly into the cloud it just left. Cross in front of its turn instead of behind its tail, or wait the cloud out. An SMG or upgraded pistol is entirely sufficient; distance and angles matter more than a pricier weapon here, as the tiers in Weapons & Rods show.
Eat between passes. If the timing genuinely will not click, Easy mode from Patch 1.0.9 cuts creature health by 25% and damage by 50%, which is covered in Difficulty Settings.
Hand in the fin
Loot the Pufferfish Tail — the fin — and take it back to the tourist under the tree. The Island 4 coordinates appear when he accepts it, not at the moment the health bar empties. That distinction catches a lot of players who sail off immediately after the kill and assume the game is bugged.
Sell the ordinary meat afterwards; values are in Fish Prices. Next on the route is the Rocks island, the Tuna, and the Albatross. The species you can catch here are in Desert Island, and the full chain sits in the Walkthrough.