ABSTRACT
The Icthyophonosis is a dangerous disease, the consequences of which are difficult to assess for wild populations of fish. This study aimed to throw the light on the importance of I. hoferi on fresh water fish, it dangerious effect in addition to its identification of isolation, characterization and the most important symptoms showed on naturally infected Oreochromis niloticus with I. hoferi showing deformity of vertebral column, darkening in color, sand paper appearance of skin, poor appetite listlessness. The young culture of I. hoferi on SDA t 10% bovine serum showing rupture of multinucleated bodies and release of spores through extra material discharge after 9 days. At PH 3.5 showing starting of hyphal growth after shours post-culturing the lyphae produce many branches, extending of the hyphae to grow and increase in length after 24 hours, migration of cytoplasm to the apexes of hypae after 3 days, rounding up of the apics of the hyphae after 7 days, finally all the hyphae rounding up to form sphericael hyphae terminal bodies after 10 days. Rounding up of the apics of the hyphae after 7 days, finally all the hyphae rounding up to form sphericael hyphae terminal bodies after 10 days and in old culture showing chlamydospores formation around the multinucleated bodies and extend to the test of sticked hyphae at 3 weeks