Biotic Filter is a resource in Warframe that can be obtained by fishing on the Cambion Dift on Deimos. After fish are caught, then can be brough to Daugher and cut into bait, giving you their various resources. The Biotic Filter is primarily used to manufacture Mutagens, Necramechs parts, and Necramech weapons.
You can get Biotic Filter from two different types of fish, the Aquapulmo and the Duroid. Both of these fish can be caught under different circumstances, in different places.
Aquapulmo
The Aquapulmo is a rare fish that can be found at surface hotspots during the Vome cycle. It will spawn in the presence of Processed Fass Residue. When cut for bait, the fish will give one Biotic Filter, regardless of the size of the fish. Processed Fass Residue can be purchased from Daughter at the Necralisk for 300 Standing.
Duroid
Duroid can be found at cave hotspots during the Fass or Vome cycle and will spawn more in the presence of Vome Residue. Vome Residue can be found on the surface of the Cambion Drift after the Vome cycle ends and the worm explodes.
Remember, if you are fishing and have active Resource Booster, it will double your catch, as will the Smeeta Kavat’s charm.
How to get fish bait
When Fass and Vome duel in the Cambion Drift, the losing Wyrm’s body will be blown to pieces, scattering residue across the map. Both of these residues can be picked up and used as Bait for the Infested Fish and can be accessed in the fishing menu. To open the fishing menu, just equip one of your fishing spears.
You will need to drop the bait into the water that the fish flow through when they are not floating through the air. You cannot catch the fish when they are in the water, and can only do so when they are floating.
You can bring your fish to Daughter, located in the Necralisk, and marked on the minimap by a small fish symbol. You can cut the fish here, and trade in parts for Daughter tokens that you will need to rank up with the Entrati Syndicate. You can also get the Spari spear from her, which is the best way to catch these fish.