Silver eyes just signifies if it's part vieja. You can have silver eyed FH's that are still fertile but for some reason having veija blood in them tends to lower the chances of them being fertile. Red eyes generally have a higher chance of being fertile but like AdrianV205 mentioned it's not a 100% certain. The only time you will know for certain is when you breed it to a "proven" female breeder, granted not completely fool proof but if your breeding with a "proven" female and you don't get any fry after 5-6 trys at breeding them, then ya most likely got an infertile male.