You cannot tame polar bears in Minecraft
Polar bears are not tamable like wolves, cats, or parrots
You can breed polar bears only if they are adults and have a nearby cub? No, polar bears cannot be bred either
You can keep polar bears in an enclosure using leads, boats, or minecarts
You can protect yourself by avoiding their cubs, since adults become hostile when cubs are nearby
You can feed them fish in some versions? No, feeding does not tame them
Use fences or walls to contain them safely
Use a lead to move them short distances
Be careful around baby polar bears because adult polar bears may attack if threatened