Over the last few years, study of attachment to confirm the histological impacts induced by some copepods and monogenean parasites of fishes are interest most of parasitologistes. With this present book, it has been satisfactory explanation as to how these parasites attach themselves sufficiently strongly in the gill chamber of their fish hosts to prevent dislodgment by the gill ventilating current. Moreover, this strong attachment of these parasites to their hosts leads to study the mode of attachment and histopathological impacts resulting from this type of attachment.