My understanding for the reason why it is so hard to get Asian arowana private import and ownership made legal in the USA is that the US Endangered Species Act does not distinguish between any of the class 1 CITES animals on the list (rhinos, tigers, etc.). There is a blanket ban on the private importation of all Class 1 CITES animals (unless it is for educational/institutional use). There are some additional issues as well (i.e. verification of captive breeding and allocation of $$ collected via business for habitat protection), but it is the blanket nature of the Endangered Species Act that is the main problem. In order for Asian arowana to be removed from that legislation, a new draft bill dealing specifically with Asian arowana would have to be released on the floor of the congress. This means one would need to find and lobby a specific US congressman (either Democrat or Republican) to use their time to draft a bill and submit it to the congress for approval. Such a bill would need a majority of congress to support it before it could then move to the US Senate. Only after passing both houses of government could it then be ratified into law.
I think a member of congress is only going to take on the "legalize Asian arowana" cause if he/she can see that: a) they or their party will get some votes; b) it is in the national interest of the USA. This is such a narrow special interest I can't see any member of congress wanting to get involved.
Mind you, arowana rhymes with marijuanna, and so maybe a bill "legalizing arowana ownership" could pass with the help of a member of congress from Washington state or Colorado.