It seems like they are not very fecund. Fishbase lists population doubling time as 4.5-14 years! That is very high...

The concern of them establishing a population in America is real. A species like this is a big candidate. Bright colored when small and becoming duller and boring as they grow. Many aquarists would simply tire of them and release them into the wild. That is why I still see brightly colored goldfish swimming in the Potomac...

The biggest thing would be to study temperature tolerance. Then determine if they are usable as an algae control method and then work on producing triploid fish like they have with grass carp. Whether anyone would ever take the time and effort to do such a thing? I doubt it...