1300 HP (Water Temple, War in the Depths of Hyrule)
Tears of the Kingdom
Mucktorok was summoned by the Demon King in order to prevent Sidon from obtaining the Secret Stone within the temple. When Sidon arrives with Link to the Water Temple, they witness Sludge emerging from a singular spot right at the base of the Great Wellspring, which they deduce to be the main source. Zelda is not witnessed here like in other chapters, but is frequently mentioned in passing by Sidon and King Dorephan.
After switching five water valves throughout the temple, Link and Sidon are able to activate the main wellspring, completely washing away the Sludge at its base and revealing the mischevious and diminutive Mucktorok. Upon defeating it, Sidon awakens as a sage and obtains his secret stone. The Sludge throughout Zora's Domain disappears, and the previously sludge-wounded King Dorephan is fully healed. This also automatically completes the Mired in Muck side quest if it was not previously started or finished.
Mucktorok is also posted in the Depths of Hyrule, being one of many monsters defending the Demon King's location. Link must fight it if he did not fight the Mucktorok at the Water Temple, but if he did, then Sidon will deal with it for him, allowing Link to skip this fight.
Once it is defeated in the Hyrule overworld, it can continue to be encountered in specific arenas in the Depths, where upon death it will drop a pile of Octorok materials, including Octorok Tentacles, Octo Balloons and Octorok Eyeballs.
Mucktorok is for the most part a fairly easy encounter compared to the other bosses around it. This is helped by the fact that Link will have fairly easy access to Zora weapons before approaching the Water Temple at all, allowing for a considerable natural damage buff with how often Link comes in contact with water during this part of the Main Quest. During the first phase, Mucktorok will swim around the arena in the form of a Sludge Shark, slamming the ground to create Sludge shockwaves and firing a Sludge Beam across the arena. It will be properly exposed when hit one to two times with any water source, including with Arrows fused with Splash Fruit or Chuchu Jelly, a weapon fused with Opal, or Sidon's Power of Water, which is always a guarunteed single shot. It will then attempt to clumsily flee from Link, where it can then be easily reached and attacked once so it falls down, and attacked further for easy damage. If using a Zora weapon fused with the strongest possible material, this phase can be cleared in a matter of seconds.
When Mucktorok is brought down to half health, it will then jump into the center of the arena and cover the area in pools of Sludge including usually upon Link's location, momentarily stifling movement, before resuming the Sludge Shark form. Link has the option to clear as much of the Sludge in the arena as he can with water-type attacks, as when the Sludge Shark is hit once or twice with water and Mucktorok again becomes exposed, it will this time disappear into and swim jump across every existing pile of Sludge, increasing its evasion ability and making it more unpredictable to track. It will also continue to spread more Sludge across the arena during these moments until it is otherwise further attacked or retakes the form of the Sludge Shark. Sidon's Power of Water and Arrows fused with any Eyeball can provide the needed hit to stun Mucktorok once again, where he can then be continuously hit until defeated. Zora Weapons fused with strong materials can again drastically cut down on the time needed to defeat this boss.