Popularity of the axolotl has skyrocketed in recent years, but the question is: can I own one? The answer depends on where you live. In the United States, it is illegal to own the amphibian in California, Maine, New Jersey, and Washington D.C. You need a permit to own one in New Mexico and Hawaii. The reason for this is because they would be a large environmental threat if released into the wild.
In my second source, they say the reason for the ban in some states is because axolotls have been "bred in captivity for decades, to the point where they are no longer the same as axolotls found in the wild, both genetically and behaviorally". This means that if they are almost an entirely different species, and if they were released into the wild it could cause a multitude of problems. So, while axolotls are desirable for their cute appearance, they are illegal in some states.
https://www.axolotlcentral.com/post/why-are-axolotls-illegal-to-own-in-some-states-provinces
https://newstalkkgvo.com/ixp/341/p/axolotl-pet-illegal-states/