There are several species of “spotted” silver dollars (4-5) in the genus Metynnis (a genus comprising circa 14 species). The only two of those that are common in the hobby are maculatus and lippincotianus, with lippincotianus being far more common, at least in the USA, and in recent years.
Spotting is heavily dependent on happiness of the fish, and on “mood”, i.e., displaying to females or competitors. Although both genders are spotted, typically is stronger on males.
To the question if the spots fade with age. No they don’t. In fact, they increase with sexual maturity, but again, depends on conditions and mood, but should always be detectable in any condition. Usually single silver dollars in a tank, or unhappy fish do no show well the spots, or at all. A nice group including both genders and well feed in a suitable tank will show lots of spotting.
By the way, some people consider a third species as “spotted” -, Metynnis altidorsalis. They are not truly spotted, the dark markings are more like large irregular blotches (irregular in size, and in distribution).
There are at least two additional spotted dollars, but they dont make into the hobby. The most spotted of all is Metynnis anisurus, which I have only once seen offered for sale online, in many years.
Cheers!
