Samar Saad Seoud^1,, Viola H. Zaki¹, Gamal E. Ahmed², Nevien K. Abd El-Khalek¹

Amyloodinium ocellatum, a dinoflagellate which causes one of the most serious diseases of warm water marine aquaculture. The parasite produces a powdery or velvety appearance on infected fish, and the resulting disease is commonly referred to as “marine velvet,” velvet disease, or Amyloodiniosis. The organism is a dinoflagellate ectoparasite and has been reported in a wide range of marine and estuarine fish. It is one of a very few organisms that can infect both teleosts and elasmobranchs [2]. This makes it a concern for public aquaria. This ectoparasite can be found on gills and skin (body and fins) of host fish. It can cause devastating disease and mortality because the organism is able to reproduce quickly when fish are crowded, especially in closed systems. This parasite has a broad host and geographic range, causing fish mortalities in tropical and temperate environments. Rapid spread of the parasite and high mortality are common in cultured fish if the organism is not recognized and treated early in the course of an outbreak. One of the most important of the ectoparasitic protozoa is in this respect, the present study was aimed to investigate the occurrence of Amyloodiniosis among cultured European seabass (Dicentrarchus labrax L.; Moronidae; Perciformes) fishes. This work was carried out on 1065 European seabass fishes of different life stages (546 fry-222 fingerling and 78 adults) which were collected in different seasons of the year. Cultured fish were collected from different marine farms in Egypt during the period from April 2015 to April 2016 and subjected to full clinical parasitological and histopathological examination studying the environmental stressors surrounding examined fish and their association with A.ocellatum infestation Study the ecological factors affects Amyloodiniosis. As well as examining the antiseptic activity of hydrogen peroxide against the ectoparasitic protozoan A.ocellatum as a trial for treatment.

Amyloodinium ocellatum, european seabass fishes, infestation, treatment, Dicentrarchus labrax L., ectoparasitic protozoa, histopathological, parasitological, Egypt