There's a lot of debate over exactly which fish is the true
rivulatus. The fish Ronnie M has is the one that Alf Stalsberg considers to be the real thing, which Americans call Silversaum. However, there is some belief that this fish and the Goldsaum are actually the same species, just different populations. Silver edged individuals have come out of spawns of Goldsaum from Ecuador. Goldsaum is also found in northern Peru, but those populations are reported to always be red/gold edged. The Goldsaum was identified as
Andinoacara rivulatus by Kullander in 2003, though Stalsberg considers them an undescribed species.
The original Green Terror came from further south in Peru, and was originally mistaken for
rivulatus because it was said to have come from the north, near Ecuador. However, unlike the two "Saum" species, which have shiny scales with black spots, it has different scales in a netlike pattern of black with shiny centers. It is known in Europe as the "Silbersaum", which some have confused with the fish Americans call "Silversaum". Both names have the same meaning, but are different fish. The original Peruvian Green Terror was just described, and is now
Andinoacara stalsbergi, after Alf Stalsberg who collected specimens of all three forms from their natural habitats, helping to define their ranges.
I just noticed that Dwarfpike and I were writing at the same time!

We differ slightly in that the describers of
A. stalsbergi consider the Goldsaum to be
rivulatus, but no one has compared the type specimens of that species with any of these fish. They did not mention, and apparently were not aware of, the silver edged Ecuadorian populations.
Whenever something seems too good to be true I find it's best to shoot it, just in case. - Fiona Glenanne on Burn Notice