but even if americans are practically giving it away the shipping costs would be huge to transport so many fish across the world, likely cheaper to rely on the communal fish markets
Considering the return that could be made by selling all that carp, it should be able to make up for the transport cost and should be able to also make a decent profit.
Besides, if anything the Chinese would probably interested, as they're having some problems just maintaining declining carp numbers in their own waters.