Microscopic examination has to be envisaged Microscopic whenever external observation proves insufficient to arrive at a correct conclusion on the cause of the disease. You can teach yourself how to use a microscope, but it is best to do this through a training course or to purchase our book & DVDrom "The New Illustrated Guide to Fish Diseases" with 1000 colorphotographs and 62 videos (see page 10). Instead of performing the microscopic examination yourself, you can