Quick Scoop: In Fisch, the tainted mutation is generally obtained by using the Bloomspire: Twisted Toxins rod, which gives about a 40% chance to roll the mutation on each catch.

How to get it

  1. Get the Bloomspire rod first.
  1. Upgrade it with a Toxic Lotus.
  1. The Toxic Lotus is obtained by planting a Rotted Seed in the Living Garden.
  1. Once upgraded to Twisted Toxins , fish normally and each catch has a chance to become tainted.

Requirements mentioned

  • Some guides say you need to unlock Bloomspire before using the upgrade path.
  • One guide says Bloomspire requires level 150 and 100% completion of the Toxic Grove bestiary.
  • Another source says the rod can be purchased in the Living Garden area, with one video claiming a price of 1.2 million.

What to expect

  • The mutation chance is not guaranteed, so the method is mostly about grinding catches once you have the right rod.
  • Different guides agree on the same core loop: Bloomspire rod + Toxic Lotus = Twisted Toxins = tainted mutation chance.

Mini note

The exact unlock details vary a bit between guides, but the most consistent route is still the Bloomspire → Toxic Lotus → Twisted Toxins path.

TL;DR: Get Bloomspire, upgrade it with a Toxic Lotus from a Rotted Seed in the Living Garden, then fish with Twisted Toxins for a roughly 40% tainted mutation chance.