Jetfish have medium-sized black bodies and two neon purple eyes. Framing their bodies are shorter pectoral fins, longer tail fins with joints at the midpoints and a vent which expels water, around which the tail fins are draped. Their eyes are ring-like in water, but constrict and take on a much smaller, circular shape when on land. Additionally, their heads may sometimes sport whiskers.
Jetfish are by far the quickest way to move through water, and even grant immunity to leeches, both of which are incredibly useful properties for moving through Shoreline. However, they must be grabbed onto first in order to be used, which can prove challenging due to their deft movement and (by default) harassing behaviour towards Slugcat. Due to this, care must be taken to approach them, especially when in groups. Blue Fruit, when dropped into the surface of the water, lures them up, granting an opportunity to grab on.
Jetfish attempt to harass the player at neutral or lower reputation. They ram into Slugcat, temporarily stunning and knocking anything held (including other Jetfish) out of their hands. This behavior is much more dangerous in packs, as they can easily stun-lock the Slugcat, resulting in them drowning. There is a Remix toggle to keep Jetfish from knocking items out of the player's hands, but does not disable the harassing behavior.
When grabbed, Jetfish provide a substantial boost to mobility in water. They are easily controlled and quite responsive, allowing for safe passage through flooded tunnels that are impassable alone. They are also able to outrun Leviathans, making traversing long stretches of water in Shoreline considerably less risky. The jet of liquid they expel creates a large amount of momentum, which can be used to propel through the air. As a drawback, Jetfish are very cumbersome when held on land, and too heavy to be carried up poles by Monk and Survivor. Other items cannot be held while riding one, unless glitches are used.
Jetfish's pectoral fins can take on a variety of shapes whereas their tail fins vary only in length, thickness and joint angle. The same is true for the 0-3 sets of whiskers found at the fronts of their bodies, which may also protrude in different directions.
Three sets of long whiskers
Two sets of short, thin whiskers
A set of whiskers positioned near the eyes
Three sets of horizontally angled whiskers, and very short side fins
Jetfish are immune to Leeches and extend this immunity to Slugcat when riding one.
Jetfish deal a small amount of damage when ramming, meaning it is possible for them to accidentally kill each other when doing so.
The Hunter is strong enough to perform a slide pounce while holding a Jetfish. Doing so causes them to travel approximately two and a half times farther compared to a normal slide pounce. This property can be used to easily obtain the JellyfishArena unlock.