It is illegal for all shipping to the US unless you have bought an import permit (a couple of hundred bucks last time I checked) and pay an inspection fee for every box at an approved port of entry. This means you have to pick the box up at an approved F&W staffed international airport. 10 years ago, it cost around $230 US for someone to import a fish.
If you are caught sidestepping that, the fines are heftier than the fees.
It's federal, not state.
I know of European killie people who have shipped to the US since those laws (they are 20+ years old, back to GW Bush), and had the packages get through. But it's smuggling and is the luck of the draw. Since I travel through the US sometimes, I won't ship fish there. It shut down my fish selling business, but you roll with the punches.
I've also had more trouble getting killie eggs eggs out of the US than from anywhere else - the boxes don't ever arrive when mailed from the US. They vanish. From Europe, they come to Canada easily and quickly, but the US has a very closed border.