Bladderfish (Subnautica)

The Airsack, formely known as the Bladderfish, is a life form belonging to the fauna category. It is catchable and edible, mostly populating in the Safe Shallows.

The Airsack stand out in comparison to other small fishes, as they can be used to craft filtered water. As a result, Airsacks are the second best source of H2O, after disinfected water.

Being slow and passive, Airsacks are easy to catch, especially during night time, when they are next to immobile due to their diurnal properties.

Appearance
The Airsack is a small creature comprised of a long, extremely thin main body with large translucent bladders on the top and bottom. These bladders have slim tube-like structures protruding out from their outer edges, and they undulate as the Airsack moves.

The Airsack's head is bright orange and ovular in shape, possessing a pair of large eyes and no discernible mouth. Its air bladders appear to have a faint violet bioluminescent glow.

Data Bank Entry
Assessment: Membrane may have applications as a natural water filter
 * 1) Semi-permeable membrane: Body consists of an oxygen- and water-filled, semi-permeable membrane. No oral cavity detected. Membrane may filter plant matter from the water.
 * 2) Open-ended vascular tubing: Can be angled and contracted to pump out water and achieve low-velocity, guided propulsion. No fins identified.
 * 3) Mostly oblivious threats, its only identified defense mechanism: it is 95% cartilage.

Trivia

 * In Freedom mode, you can click on an Airsack to replenish your oxygen.