• Knock out the koi and take a small snip from the gill. Place the gill tissue onto a slide for examination.

• If you keep koi you should have a microscope or at least know where to borrow one. Some koi clubs do provide loaner scopes. If you are from the East coast area try the Mid Atlantic Koi Club they might be able to help.

• P1000712 is a picture of a very healthy gill. The lamella are fully free without mucous. P1000711 is the same gill only with a lower power. When examining gills one wants to find this type of view in the scope. P100717 and 716 represent gills with mild hyperplasia – thickening of the mucous layer. P1000728 details a full lamella with moderate hyperplasia under relatively low power.