US F&W confiscations get allocated to institutions with the correct paperwork to take on the animal in question. None get passed on to private owners and none get put down unless they absolutely have to.
Most Zoos and Aquariums work very closely with local gov't authorities in this respect. I was on a first name basis with several of the locals in Texas while working there. I was even called in to ID fish in question from time to time. It's midn boggling how many things need paper work. Even "legal" animals in the US may need some random form to be transported across the line. We got a lot of African cichlids that way. 99% of the time, there is an institution willing to take them legally.
As for Asian Aros, we had the permit for the at the Dallas World Aquarium, so we housed dozens (in all size ranges). As an example: F&W had a line on a guy who kept trying over and over.....we must have pulled 50 or so from him over several months. It was a person who was bragging about it in an online forum, so it made it easy to find him. A lot of ours came from attempts at bringing them in from Mexico, but we did get some coming into Cali from various Asian Islands.