Ich (Ichthyophthirius multifilis) is probably the most common parasite in ornamental fish. It is one of the few microscopic parasites that can be diagnosed without a microscope, because it has one life stage that produces salt grain sized ‘cysts’ that are easily visible with the naked eye.

Ich (Ichthyophthirius multifilis) is probably the most common parasite in ornamental fish. It is one of the few microscopic parasites that can be diagnosed without a microscope, because it has one life stage that produces salt grain sized ‘cysts’ that are easily visible with the naked eye.