Another cool clip from River Monsters : Season 5 has been released. This one features Jeremy Wade catching a small Vampire Fish in some rapids. You may also know the Vampire Fish (Hydrolycus scomberoides) as a Payara. It is a cousin of the Piranha with a more vicious set of teeth and the speed to live in even the fastest rapids.
The fish featured in the later part of the clip are the Hydrolycus scomberoides species but the smaller one he catches might be a Hydrolycus armatus. I am not sure on the id on that smaller one, comment if you know for sure. It could also be one of the other Hydrolycus species - Hydrolycus tatauaia or Hydrolycus wallacei. After looking at photos I can’t be sure myself, the specimen appears to be quite young so it’s harder to tell.