ABSTRACT. In March, 1997, 150 fresh fish specimens from the waters of Arabian Gulf, 95 of fish belonging to Groupers, Epinephelus aerolatus (local name Simman) and the other 55 fish specimens belonging to Emperor lethrinus sp. (local name Sheiry) were subjected to parasitological examination. Free floriceps Trypanorhyncha plerocercoids larvae were found in the flesh, while encysted forms of these larvae were found in the body cavity and mesenteries. The incidence of infection was higher in the Lethrinus sp. (34.5%) than Epinephelus sp. (24.2%). Intensity of infestation in the muscular tissues was higher in the muscles of the caudal peduncle; head and around the vertebral column than in the abdomen and trunk regions. Histopathology of the infected muscular tissues showed pronounced tissues destruction with intensive inflammatory reaction characterized by focal degenerative and necrotic changes with evidence of hemorrhages and cellular infiltration mainly lymphocytes. Over 350 encysted plerocercoids blastocysts of floriceps sp. could be counted from the peritoneal cavity and around the internal organs in heavy infested fishes with signs of fibrosis and adhesion.

These case studies endeavor to report incidences of caudal fin deformities in several commercial fishes living in natural populations in the Saudi Arabian coastal waters of the Arabian Gulf. Two groups of anomalies were observed, slight and severe. The carangid species, Parastromateus niger (Bloch) and the soleid species, Euryglossa orientalis (Bloch & Schneider), had slight cases of caudal fin abnormalities, while the species Oreochrromis mossambicus (Peters), Epinephelus stoliczkae (Day), Diagramma pictum (Thunberg), Cephalopholis hemistiktos (Rüppell), Lethrinus nebulosus (Forsskål), and Lutjanus sanguineus (Cuvier) had severe deformities. The abnormalities were assessed by morphological diagnosis. None of the cases was fatal as they occurred in adult individuals. The possible causes for these deformities as well as the suitability of this kind of case study for environmental monitoring are discussed. Further studies should be conducted from the perspective of pollution.

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