I dont know about Texas but they are related to the Armatus,tats and scomberiodes and they can grow to at least 12 inches in length.They eat small fishes,arent very aggressive and can actually be bullied by the wrong tankmates.When our stores get them they label them as either vampire or sabertooth tetra and sell from twenty to thirty dollars from two inchers on up.
I havent seen any on any vendors lists but you can always pm them.I dont have pictures but Vamptrev and DBjunkie have posted pics before.Place the fish name in the search feature on the left and you shpuld find plenty.