Fermented Spider Eye

The Fermented Spider Eye was first added in the 1.9 Pre-Release 2. It can be crafted from a spider eye, brown mushroom, and sugar on a crafting grid (shapeless recipe). They cannot be eaten unlike the regular spider eye. They are used in a brewing stand to make Weakness potions. All potions made by Fermented Spider Eyes have negative effects.

Crafting
The position of the items does not matter.

As a Brewing ingredient
! Fermented Spider Eye + Potion of Poison = Potion of Harming
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Trivia

 * Fermented spider-eyes are used to make negative potions, which makes it useful for splash potions to use against enemies.