ABSTRACT: The occurrence of a spontaneous tumor affecting the guanophore iridocytes of the Red Sea silverside Atherinomorus lacunosus is described. The tumoral mass consisted mainly of yellowish, light-reflecting guanine platelets. The tumor infiltrated the fibers of the underlying muscle tissue, growing in whorls around them. A delicate network of capillaries provided the tumor with a blood supply. No viral particles were observed. This rare form of tumor is the first of this kind reported in a feral fish from the Red Sea.

KEY WORDS: Guanophoroma · Neoplasia · Iridocyte · Guanine · Atherinidae · Red Sea

Published in DAO Vol. 29, No. 3 (1997) on June 19
ISSN: 0177-5103. Copyright © Inter-Research, Oldendorf/Luhe, 1997