I got them off an eBay seller. They had good ratings too. But she does have Ancona on property as well. It is a small duck not any bigger than my black East Indies. Sad he might not be a purebred but still love this little duck.So, Australian Spotted ducks are supposed to all be what they call Spot in color, a mallard based pattern that involves one harlequin allele and one light phase allele. I've never bred them, but because of that it wouldn't be possible for them to all breed true and all be Spot. I would wager that nowadays most of them are really just light phase now.
They also have different colors which they call Greenhead, Bluehead, and Silverhead. Greenhead is regular Spot. Bluehead is Blue Splot, aka Spot with the addition of one blue dilution allele. Silverhead is Silver Spot, Spot with two blue dilution alleles.
So the bad news - your duck doesn't appear to be any of these. It looks like it is an extended black color, not a mallard-based color. To me, it looks blue bibbed. Maybe even blue pied. He could possibly be a cross of an Australian Spotted, but no purebred Australian Spotted ducks look like that. Where did the eggs come from?