Zapfish (Japanese: デンチナマズ, Denchinamazu) are a type of an electric catfish with the ability to produce a strong electrical current, that appear in Splatoon's Hero Mode. The player must rescue one at the end of every mission in order to proceed in the story.
Zapfish are the main power source of the Inklings' world. They were stolen and taken to Octo Valley, a hidden underground base used by the Octarians, because they are running out of power and to reactivate the Great Octoweapons. The player must rescue all the Zapfish, to be able to proceed to new areas. The goal of the Hero Mode is to save the giant 100 year old Great Zapfish, which is the power supply of Inkopolis.
In Splatoon 2, eight Zapfish spawn were used in some levels to power the same amount of energy generated by one adult Zapfish, and each of them were kept in spotlight-like containers. These are well known as Mini Zapfish.
A Zapfish is found near the conclusion of every campaign level, enclosed in a glowing sphere and sitting on a light bulb-esque pedestal. The player must shoot the sphere with ink until it bursts, releasing the Zapfish. In boss levels, the Zapfish will be seen hanging over a pool of Octarian ink in a similar container before the boss' tentacle lashes up to grab it and drag downwards to commence the boss. Once the boss is defeated and blows up in a huge splash of the player's ink, the Zapfish will be left behind to be claimed just like in the other stages.
Zapfish appear similar to an anglerfish, and a light bulb's filament. They seem to have a large head with two small eyes, two nostrils, and a big pair of orange lips. Below the head is a smaller body. When a Zapfish is successfully rescued, upon replaying that mission, the Zapfish is replaced with a plush replica with a blue cap. Also, the victory scene of the protagonist will be different from the one shown when they first rescued the real Zapfish.
A good example being in the Hero Mode of Splatoon 2. When a female Agent 4 rescues a Zapfish, she hugs it close with an overjoyed smile on her face, even when wearing additional armor. When replaying the mission and rescuing the plush replica, she simply jumps up into the air with a satisfied smirk at having kicked Octarian brine again to clear the stage and rescue the plush replica.
The Great Zapfish is a large Zapfish that first appears at the beginning of the battle against DJ Octavio when it gets sucked into the Octobot King. After the player defeats DJ Octavio, the Great Zapfish appears above Inkopolis Plaza.
In Splatoon 2, the Great Zapfish has been kidnapped again by DJ Octavio and his Octarians, along with Callie of the Squid Sisters. After DJ Octavio is defeated, Callie and the Great Zapfish are rescued, and the Great Zapfish can be seen either wrapped around Deca Tower, lying on the train tracks above and behind Grizzco Industries, or flying overhead, which is easily noticed as it makes the same noises similar to its struggling before being sucked into the Octobot King II when flying over Inkopolis Square.
- Zapfish in the Octarians' spheres are surrounded by electrical charges, likely indicating that they are generating power for Octo Valley.
- The Japanese name "Denchi Namazu" (電池鯰, デンチナマズ) literally means "Catfish Battery." Similar to electric eels, some catfish produce an electrical discharge to defend themselves.
- In the map Piranha Pit around the 0:45 second mark in Turf War, you can see the Great Zapfish in the sea.
- When the player completes a mission he/she has already completed, a fake Zapfish will appear instead of a real one. The player pats the Zapfish a few times during the end of the level music. You can see a gif below.
- Before every boss battle, an Octarian tentacle is shown to grab the Zapfish, if the player has already completed the battle, it will be replaced with a fake Zapfish. The tentacle that grabs the Zapfish also sports a cross-shaped scar on it similar to that seen on DJ Octavio.
- The Great Zapfish resembles the Pokemon Whiscash.
- Zapfish were used in a dungeon in Super Smash Bros Ultimate. In this game, the Great Zapfish also appeared as a Support Spirit.