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That guy is a Hydrolicus Scomberoides,sold as Vampire Tetra or Sabertooth Tetra in U.S. fish stores.By the way,how much are they being sold for over there.
payara generally refers to the hydrolycus species.
scomberoides
tataiaua
armatus
biggest growing and most aggressive is the armatus.
grows to 3 feet in length i think.
also is the only one that grows fast.
scombs and redtails grow slow.
the one in the picture is a scomb.
btw,i find them for 20 plus.