Photobacterium damselae causes photobacteriosis of marine ornamental yellow tail surgeon (zebrasoma xanthurum) the disease appeared and spread rapidly in yellow tail surgeon in the indoor aquarium of National Institute of Oceanography and Fisheries (NIOF) at Hurghada (Egypt). The pathogen was isolated from skin lesions in the body, and internal organs namely liver,spleen and kidney of clinically diseased and moribund fish using tryptic soy agar and thio-sulphate citrate bile salt sucrose agar plates. Lethargic, off food, hemorrhagic spots on skin, skin depigmentation, and fin rot were the main clinical signs appeared on the naturally infected fish. All isolates of the bacterium constituted a homogeneous phenotypic group and were identified by morphological characterization, biochemical tests and API20E as Photobacterium damselae. The isolated strain was sensitive to Sulfamethoxazole Gentamycin, and Streptomycin.
