Bucket of Axolotl creates new colored Axolotl when put in bucket and put back out

When you pick up an axolotl in a bucket in survival mode, if you put it back down it turns to a different axolotl, so If I want a pink axolotl in a bucket, and I put one in my bucket and place it back down, there is a chance that it is no longer pink. It changes the axolotl every time you put it in a bucket