Infected Fin

Fins that make tames swim faster

Players collect Infected Fin for the Infected Barnacles it helps create, which raise a creature's swimming speed. The wiki ties this body part to the Aquatica release, and our records list it for ARK: Survival Ascended. In-game it is described as "An infected fin. Can be used to apply infected augments to creatures." Survivors and tames can also eat it for a short buff.

Where Infected Fins come from

The wiki names the Abyssal Stegosaurus as the source: kill one and harvest the body. They live in the Abyss biome, and lower-tier Rifts spawn them as well. Corpses in corrosive areas also yield fins plus other infected parts, but harvesting one all the way brings a spore debuff resembling Aberration's fertile spores.

Fin barnacles

At the Infectarium, fins go into Infected Barnacles, and a barnacle made with them raises the swimming speed of the creature that receives it.

Eating a fin

Eating a fin gives a survivor 10 food but deals 25 damage. For 30 seconds the survivor moves faster, while food and water drain rises by roughly 20%. The icon claims a melee damage boost as well, which the wiki says seems to do nothing. Eating another fin before the buff ends does not stack it; the timer simply goes back to 30 seconds. A tame that is force-fed a fin gets faster movement, takes no damage from it and gains no damage output.

Weight and spoiling

Fins weigh 0.1 each and stack to 100, so a full stack comes to 10. The wiki classes the fin as meat with a spoil timer.