The Tarr

 are the one of the main threats of Slime Rancher; the others being Feral Slimes, and Slimes that are harmful but not hostile. They can spawn anywhere from any Largo that eats a Plort unlike its own.

Slimepedia Entry
Slimeology: ''The Tarr are formed when a Largo eats a Plort unlike the ones it produces (ex. a Pink Tabby Largo eats a Honey Plort). A terrible transformation occurs that turns the slime into a sludge filled with a swirling, prismatic array of colors and a relentless appetite. The Tarr seek only to consume and replicate. Because of this it can spread rapidly throughout the ranch.''

''The only way to stop a Tarr (outside of incinerating it or throwing it into The Slime Sea) is with fresh water. One splash will stop a Tarr from spawning new Tarr, and repeated splashes will destroy it entirely. However, one splash of fresh water does not kill the Tarr and it will continue to expand. ''

Alternatively, many ranchers recommend running away with their arms waving, screaming.

Rancher Risks: ''The Tarr are the single biggest threat to ranchers. The Tarr will seek out slimes to consume and replicate themselves, but also devour chickens, rot crops in their proximity, and even devour ranchers!''

Plortonomics: ''The Tarr produce no plorts, only more Tarr. And then more Tarr still.''

Tips

 * Tarr are weak to Water, whether shot by it or when immersed in water. It is recommended to get the Water Tank upgrade for the Vacpack and keep it filled with water at all times. During the day Tarr can be killed instantly with a single shot of water. At night they gain more health, requiring them to be shot twice to dispatch them; the first shot nullifies their reproduction ability, indicated by the loss of their rainbow colouration.
 * If the player doesn't have Water they can vaccum the Tarr to shoot it into the ocean instead or into an Incinerator. If the ocean is too far away, simply shoot them as far away as possible.
 * The Pulse Wave Upgrade can also be another way of avoiding Tarr since it can keep them away if they get too close.
 * Tarr are marginally less threatening than Feral Slimes, since they target other Slimes as well as the player and can be dispatched with water. If there are too many Feral Slimes in a Danger Zone, it may be worth converting one to a Tarr, have a Tarr outbreak, then shooting the Tarr with water.
 * You can put Tarr in a Corral, but it's not worth doing so because they can jump until they break the Air Nets, do not produce Plorts, and despawn.
 * Certain areas are more prone to Tarr outbreaks than others. The last area of the Dry Reef, for example, often gets filled with Tarr because of the four types of slimes spawn there. The diversity of Slimes in The Moss Blanket and most especially in The Ancient Ruins often cause a lot Tarr outbreaks to happen as each zone is filled with a lot of food that allows the Slimes to produce a lot of Plorts.
 * If the player manages to hold onto a Tarr for 15 seconds, they unlock the Achievement: Once Bitten, Twice...Bitten.
 * In The Glass Desert, the protective barrier produced by restored Oases damages and quickly kills Tarr when they form, or enter the barrier, making them safe spots from Tarr outbreaks.
 * The Tarr do not eat Gordo Slimes.

Trivia

 * Shooting a Tarr onto a #1 Slime Stage is a requirement for the Best of the Worst achievement.
 * Tarr is an acronym for Those Awful, Ravenous, Rainbows.
 * Tarr is a direct reference to tar, a black substance that is created from organic materials.
 * Plorts are considered to be "organic wastes" of Slimes therefore supporting this reference as Tarr are made when a Largo eats a plort unlike its own.
 * In the prototype version, the Tarr's design had a dark colored slime with a drooling face and feral eyes.
 * Tarr cannot be equipped with Fashion Pods.

Changes

 * 0.3.5: Flashes red each time it is hit with water.
 * 0.3.0: Now when it dies, it produces a rainbow explosion.
 * 0.2.5: A bug causing their music to still play after them disappearing has been fixed.
 * 0.2.3: Tarr now react to being in water as if they were hit with it.
 * Before 0.2.0: Implemented in the Prototype Version.