Yup, it's just a slight red trim on the dorsal fin. Good luck with your search, I've got 6 and would be happy to get rid of 4 if a pair forms. Unfortunately, they are pretty slow growing and aggressive, so I don't know when/if that will happen.
yeah i was kind of thrown off by its markings as well but my arg was already around 4.5in when i got it so i didnt know if they changed their markings as they got older as most vieja seem to look very similar as juvies and that fish does look like it has little black dots, but yeah that sucks its not what you ordered, another way to help with shipping costs is to find someone in your area to order with so you guys can split shipping. you can also look on aquabid and see what you find on there but yeah rapps is great but yeah shipping is a bit much if your not splitting with anyone and only wanting 1-2 small fish
oh and my arg also has slight red coloring on the tips of his dorsal