I have 1 also sold as Red Tail Cuda - the term Freshwater Barracuda is used to describe several Charciform fish from Ctenolucius Hujeta to Acetrorhynchus Falactus and Brycon Dentex as well a few others. Can't always go by common names when looking for specific fish.
Brycon Dentex gets a robust 16" in the wild, they are "garbage can" eaters, readily except just about anything from flake to pellet, prepared foods to live. They are shoaling fish and particularly aggressive - even amongest their own. They are very active open water swimmers/hunters, in my case almost non-stop. Seem to grow rather quickly so the bigger the tank the better. The Dentex has a silvery body with red and black fins, a long black tail spot that streches horozontally about 1/4 to 1/3 of the body is one it's most defining markings amongst it's species. The Dentex will not have a black horizintal line growing thru the eye - I believe that species is Brycon Whitii. As juvies they seem to be often mislabeled because they do closely resemble a mature Ace. Falcatus however as they grow their body structures change to little semblence of an Ace. As adults theres no real comparison at all. As juvi's look to the anal fin - Dentex will have one that streches from the tail fin where as Falactus will have what looks like a rudder of a boat, the Ace.Fal. anal fin is almost a carbon copy of it's dorsal as juvies. I can't honestly say the do well in groups or not as I only own one and he's a juvinile. So far I find this charciform to be quite enjoyable.