How to Really Fish Sharpen Knife: Fisherman Joe Upgrade Guide

Sharpen Knife is a knife upgrade sold by Fisherman Joe in How to Really Fish. Joe is shown on Forest Island in some walkthroughs, while a full-run account places him on Island 2, so confirm the NPC's name label in your session before buying. The upgrade was reported at $15 — roughly the value of two cooked Carps — and is worth considering before the Giant Crab fight. What the purchase actually changes is not documented by current reports: check the displayed cost and the item description in your own session after buying.

Where Sharpen Knife is offered

Fisherman Joe buys cooked catches and sells upgrades through the same interaction, so you can sell fish and browse upgrades like Sharpen Knife in one menu. His island placement differs across recorded runs; check the NPC label and shop contents before treating either location as fixed.

Reported cost

Two September 2026 reports list Sharpen Knife at $15, described as roughly the value of two cooked Carps. These are dated third-party reports, not a verified current shop price — budget using the price displayed in your own game and the cash you actually have. Cooked Carp values themselves vary (reported between $8 and $11), so the "two cooked Carps" framing is approximate.

When it's worth buying

The knife is the weapon players use against the Giant Crab boss on Forest Island, so money and upgrades matter most before the crab is woken. The recommended loop:

1. Collect clams and fish for Carp (plus Emo Fish and Bream).
2. Cook every catch at the campfire.
3. Sell to Fisherman Joe.
4. Buy Sharpen Knife before the Giant Crab encounter appears.

What the transaction does and does not confirm

Reports establish Sharpen Knife only as a named purchase option in Fisherman Joe's shop. No verified damage figure, before-and-after equipment state, or item description comparison is available — the upgrade is a reported option, not a required purchase or a proven optimum. After purchasing, check the displayed cost and item description in your own session rather than assuming a guessed percentage increase. Whether the upgrade can be repeated, stacked, or persists across runs is likewise not established, so treat each purchase as something to verify in-game.