Yeah, by 3 inches GSH should be sexually mature. 3" GSH are actually the best spawners. As GSH age they can be afflicted with an ovarian parasite, Pleistophora ovarie. This greatly reduces their spawning success. The parasite isn't found in all populations and doesn't seem to affect any game fish. From my research, it is also found in wild goldfish. 3" GSH are usually second year fish in their first year of maturity and have not been affected by the parasite yet.
