Ahmed I. E. Noor El Deen, Mona S. Zaki, Olfat M. Fawzi

Abstract

Freshwater fishes are, doubtlessly, highly exposed to be infected by the parasitic infections which cause lots of economic losses. Accurate, early and fast diagnosis and controlling these parasitic diseases are of great importance. Nowadays, traditional methods in diagnosis are no more effective in the semi-intensive and intensive ways of culturing fish. Quick and easy spread of the infection from a district to another, even international spread is done with no boundaries. Traditional diagnosis may be fast, but it depends mainly on either naked eye remaking or wet mount examined under light microscope. The biggest disadvantage of this method is that it depends mainly on the expert that may be wrong or right. Therefore, using recent methods for diagnosis of fish parasitic diseases have become more accurate, faster and safer to prevent and control these parasitic diseases that prevailed in wild and cultured domestic or imported fishes. These recent methods include light microscopes to examine histopathological slides stained with histochemical stains, electron microscopes to examine tiny details of specific parasites, immunological tests that depend on antigen-antibody reactions, and molecular techniques which depend on DNA sequencing after fractionation and amplification of the parasites. The conventional methods for diagnosis of parasitic infections is considered the cornerstone for the identification of the parasites. While, non-conventional methods for diagnosis of parasitic infections should be applied. Molecular techniques and scanning electron microscope are considered new trends in the diagnosis of parasitic infections. Further studies are needed to investigate the strategy of diagnosis and control of parasitic infections of freshwater fishes.