Was it identified? The people running the place are generally very knowledgeable when it comes to freshwater fish. The colours would be ok for S. affinis/hilarii (sometimes seen in the aquarium trade), but the head structure is a problem. For that reason I really can't see it as a Salminus, regardless of species. It looks like a Brycon to me.
Regardless, this brings back fond memories. You probably have to be a bit fish crazy to really rate the place highly, but there are so many smaller freshwater fish that I've only ever seen there and I've visited a huge number of aquariums worldwide.
You're both absolutely right. It seems obvious in hindsight - I have no idea how or why I convinced myself this was an ill - looking Salminus. Among my photos I've found a blurry partial shot of the label identifying it as a Brycon hilarii. Sorry!
