Dolphins Addon (Concept!) this is addon for Minecraft PE which adds dolphins. These smart creatures will be in your world and replaced by chicken. Of course, you can meet with them underwater. In addictions, you can even tame some dolphin and get true friend.
developers: StarkTMA, Twitter Account
Creator of this addon was inspired by official Mojang statement, that in spring 2018, they add new Dolphin mob. Why you have to wait? Just download this addon and already get dolphins you in your world.
How to tame Dolphins?
Try to give them raw fish
How to add new mob?
As I said, dolphins replaced by Chicken, but they will be living only underwater.
For Minecraft PE 1.2 +