Blue Axolotl doesn’t spawn

I’ve tried for hours to get a blue axolotl, spamming spawn eggs, spamming the bucket, i tried to use a command that i found, but it doesn’t work. I made a machine to try and spawn a lot of axolotls and have been running it for a few hours while killing them off and hoping to get a blue one and it just hasn’t worked. I spent hours trying to breed them as well and nothing has come out of it. I’m convinced they just don’t exist.