Every now and again there is confusion in the health sections whether a koi has white spot disease.

So I snapped a couple of close up pics of males in the pond today just to demonstrate how the breeding tubercles which look very similar to white spot disease, are normally focussed around the gill covers (easier to spot if the Koi has black gills) but can spread around the entire head and even into the body. Where they do extend onto the body they form a pattern on the outer edge of the scale, unlike white spot disease which is random.

You might also be able to see them on the leading edge of the pectoral fins.

The big white mark on this one's gill I think is just a bit of pox. You can just about make out a row of tubercles on the leading edge of the pectoral fin against the black part.