Bucket of Axolotl Does not produce the same Axoltl Colour in Creative

I was testing in a creative world, and made a command block that would repeatedly summon axolotls in an attempt to get a blue one. I did, and picked it up in a bucket of water, thinking that I could now spawn blue ones everywhere. However, the bucket of Axolotl I had just created produced randomly coloured axolotls.