Acht

"Everyone, meet Dedf1sh. Previously a promising, up and coming DJ, her pursuit of breakbeat perfection eventually led her to a subterranean test facility, where she was "sanitized." Though little of her former self remains, she continues crafting DJ delicacies, and the halls of the test facility echo with her bumping tracks to this very day."

- Live from the Squid Research Lab

Dedf1sh is a musician in Splatoon 2 whose songs were released as part of the Octo Expansion. Once a normal Octoling, she entered the underground test facility and became sanitized, losing her free will.

Songs
Before the release of the Octo Expansion, a video entitled 'Catalog Mix' featuring short sections of some of the songs was made available. It includes several songs heard in the Octo Expansion and its missions. The only song that was named prior to Octotune's release was Splattack! (Octo).

Trivia

 * In her album art, Dedf1sh uses a series of turntables each with the number 8 on them and eight buttons, corresponding to an octopus' number of arms and the overall recurring number eight through the Octo Expansion.
 * The background of the album art features the Kamabo Corporation logo, also seen in places such as the CQ card and C.Q. Cumber's hat.
 * With the style of her tentacles, headphones, and colored fingertips, Dedf1sh bears a resemblance to Marina.
 * Oddly, her numbered catalog of songs appears to be missing select numbers: 3, 7, 10, 15, 17, and 18.
 * When adding the numbers from the title of each song and then dividing the total by the number of songs Dedf1sh has composed (in other words, taking the average of the remaining numbers plus an extra 0 to represent Splattack! (Octo)), the result is eight, the recurring theme of the Octo Expansion.


 * HaikaraWalker reveals that Dedf1sh's real name is "ミズタ アハト" (Mizuta Ahato) ; or Ahato Mizuta if written with the English name order, as surnames come first in Japanese.
 * "Mizuta" likely refers to the Giant Pacific octopus, or "mizudako" in Japanese, while "Ahato" is the Japanese rendering of "Acht", or German for "eight".
 * A Q&A with the Squid Research Lab from the Nintendo Dream Magazine revealed that Dedf1sh wanted to become sanitized to give up her doubts and conflicts about production and devote herself entirely to music.
 * PAUL of SashiMori has her logo on his beanie.

Etymology
Dedf1sh is a portmanteau of dead + fish, in reference to her sanitization and no longer showing vital signs. The name is likely mimicry of the DJ and musician, deadmau5. Both are stylized in leetspeak, which is a nod to computer hacking evidenced by the purposeful misspelling of "dead" and her song titles.