How to Get Blue Axolotl in Minecraft

Unlike the other four types, the Blue Axolotl can only be acquired by breeding. Here are the items you'll need for it:

2 x Axolotl 2 x Tropical Fish 1 x Breeding Pool
How to Build a Breeding Pool in Minecraft

Finally, Minecrafters should have a Breeding Pool where they can put their Axolotl to multiply quickly. For this purpose, place water source blocks on land and then build walls around the pool. While building the pool for your little friends, make sure that the walls are one block higher than the water's surface.

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If you don't make this one-block-high wall, Axolotls might escape into nearby oceans or water bodies. Furthermore, it would be a good idea to build your pool near a place where Tropical Fish are easily available. This way, players will be able to quickly to the Axolotls without wasting time.

Once your pool is ready, simply place the Axolotls inside and add the buckets of Tropical Fish. The chance of getting a Blue Axolotl is still pretty low, but you can keep breeding more Axolotls to increase your chances of getting one.

Minecrafters can also use the /summon axolotl ~ ~ ~ {Variant:4} command to get Blue Axolotls without breeding.

source: Game Rant