First Report of Ichthyophoniasis in Angelfish, Pterophyllum altum, and Histopathology Study of Infected Fish

Ichthyophonus is a unicellular fish parasite with a range of hosts and therefore a lot of economic losses. In this study, Ichthyophonus infection was reported in diseased angelfish, Pterophyllum altum. Samples were provided from three angelfish referred to veterinary hospital and examined by routine methods. The fish were lethargic with mild symptoms of chronic disease. According to a spherical shape and globular morphology of agent (characteristic spores surrounded by a thick fibrous membrane seen in squash preparations made from heart and spleen) and further histopathology and culture results, agent was described as Ichthyophonus hoferi. The result showed two main phases in the life of infecting parasites, 'active' and 'passive', the passive form is prone to convert to active. As another result, white-cream cysts were seen in infected organs. The most obvious macroscopic symptom of ichthyophonosis in angelfish was the spots on the skin and nodules in the heart. The cysts were filled with schizonts that were surrounded by fibroblasts, collagen fibers and many eosinophilic inflammatory cells. In the next step, tissue samples were also separated and incubated into Minimum Essential Medium (MEM) to see the germination of Ichthyophonus hoferi. This test was suggested for recognizing Ichthyophonus from Mycobacterial infections.