R Hobbenaghi - Department of Pathobiology, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran
A Tukmechi - Department of Pathophysiology and Quality Control, Artemia and Aquatic Animal Research Institute, Urmia University, Urmia, Iran
H Rahmati-Holasoo - Faculty of Veterinary Medicine, Urmia University, Urmia, Iran

Objective: To determine nature of white color masses on the head and gills operculum of flower horn fish Method & Materials: In April 2008, a female flower fish with clinical signs of white color masses on the head and gills operculum was referred to bacteriology laboratory of Artemia and Aquatic Animal institute of Urmia University. The fish was deceased and wet mount and fungal culture test on SDA were prepared. Then in sterile condition bacterial culture from internal organs and the white masses were taken. The specimens were cultured on TSA, Blood agar and BHA in aerobic and anaerobic conditions in 24°C. Tissue samples from internal organs and white masses were taken and fixed in 10% formalin for histopathological assessments. Results & Conclusion: Autopsy did not show any abnormality grossly. 72 h incubation did not show any bacterial growth in culture media. After 10 days no fungal growth was seen on SDA. Wet mount evaluation showed large circle similar to enlarged dermal fibroblasts. Histopathological analyses of the internal organs did not show any abnormality. Histopathology of white masses of the head and gills operculum showed giant circle cells completely similar to hypertrophic fibroblasts along with suppurative dermatitis. The results approved Lymphocystis in flower horn fish.

Lymphocystis- flower horn fish- fibroblasts- histopathology