Axolotl

Axolotls are aquatic passive mobs that attack most other underwater mobs.

Spawning
Adult axolotls spawn naturally in groups of 1-4 on any water with blocks above it below y: 63, typically in caves.

After the world generation, axolotls spawn individually uncommonly.

Colors
Axolotls can be one of five colors: pink (leucistic, referred to as "lucy" in its texture file), brown (wild), gold, cyan and blue. The blue variety has a $1/1200$ (0.083%) chance, giving the common varieties a $1199/4800$ (~24.98%) chance individually.

Baby axolotls picked up and re-spawned with a bucket did not preserve their growth stage and turned to adults before 21w13a.

Behavior
Axolotls are passive toward players and can be attached to leads. Axolotls give Regeneration I and remove Mining Fatigue when a player kills a mob that is in combat with an axolotl.

Axolotls attack all aquatic mobs except turtles and dolphins. They also attack drowned. After killing a non-hostile mob, there is a two minute cooldown before another non-hostile mob can be hunted. Axolotls prioritize attacking hostile mobs over non-hostile mobs.

If an axolotl takes damage underwater, it may feign death, dropping to the ground for 200 tick while gaining Regeneration I. Monsters ignore healing axolotls. There is a $1/3$ chance for an axolotl to play dead to recover. In addition, if either a random integer from 0–2 (inclusive) is less than the amount of incoming damage, or the axolotl's health before the damage is dealt is less than 50% of its maximum health, it plays dead.

On land, axolotls move toward the nearest water source because they die outside of water after 6000 tick. Unlike fish, dolphins, and squid, axolotls do not die on land during rain or a thunderstorm.

As aquatic mobs, they take extra damage from the Impaling enchantment.

Axolotls picked up with a bucket and re-spawned do not despawn.

They spin around at high speeds when attached to a lead on land due to a glitch.

Breeding
Adult axolotls can be led and bred with tropical fish or buckets of tropical fish. After breeding, a baby axolotl spawns and 1-7 experience is generated. The parents cannot be bred again for 5 minutes. The baby axolotl has a $1/1200$ chance to be the rare blue variant; otherwise, it inherits the color of one parent at random. Babies follow adults, and grow to adulthood in 20 minutes. The growth of baby axolotls can be accelerated using tropical fish; each use reduces the remaining growing time by 10%.

Entity data
Axolotls have entity data associated with them that contain various properties.

Trivia

 * are small salamanders that are endemic to Mexico, which are critically endangered, following Mojang Studios' trend of adding endangered species such as polar bears, giant pandas, sea turtles and bees into the game for awareness purposes.
 * Axolotls are the first amphibian mobs implemented into Minecraft. However, it was not the first announced amphibian because frogs were announced at MINECON Live 2019.
 * In addition, Rana was based on a frog.
 * Blue is the only color variant of axolotls not based on real life. The blue variant was a suggestion by user Darkiceflame on the r/minecraftsuggestions subreddit. It is a reference to Mudkip from the series.