The name Dorado is Spanish for mahi-mahi, or the dolphin-fish. The mahi-mahi has an opalescent skin that turns blue and gold as the fish dies. This may very well be the reason Dorado is sometimes called the goldfish.

Dorado is in the southern sky and was unknown to the Greeks it was the constellation of Dorado was one of twelve created by Petrus Plancius from the observations of Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman and first appeared on a celestial globe published circa 1597-8.
Dorado was taken a bit more seriously when it was included by Johann Bayer in 1603 in his star atlas, Uranometria, there are no myths associated with this constellation.

It is in Dorado that we can see the Large Magellanic Cloud (LMC), which is a satellite galaxy of our Milky Way Galaxy.