I was under the impression the "red-tailed tinfoil barb" was another name for the S. prochilodus or flagtail characin in short. They are very different from the tinfoil barbs growing to 14 inches and are characins, not cyprinids. They were mistaken as another version of the tinfoil barbs before as explained by a friend.
I think you mean Semaprochilodus taeniurus...or sometimes mistaken for Semaprochilodus insignis.
If that's true, there's yet another reason why common names are totally useless. :wall: