PREVALENCE OF BACTERIAL INFECTION ASSOCIATED WITH CALIGUS INFESTATION IN CULTURED MUGIL CEPHALUS WITH TRIAL TO CONTROL
Mohamed E. Abou El Atta and Walaa T. El-Ekiaby
Fish Health and Management Department, Central Laboratory For Aquaculture Research, Agricultural Research Center, Egypt
Received 15/ 10/ 2012 Accepted 4/ 12/ 2012
Abstract
One hundred and fifty clinically infected Mugil cephalus 40 ±5gm and 10 ±2cm in length were collected from earthen pond from Tri-angular of El Deeba, Damietta Governorate and subjected to clinical, postmortem investigation, bacteriological and parasitological examination. Also, the physicochemical analysis of water pond holding Mugil cephalus were recorded. The common clinical signs observed were lethargic, listless, cease to food, excessive mucus and nervous manifestation, infested fishes were rubbed themselves on solid substrate in attempt to dislodge the crustacean parasites which appeared attached to gills, skin & fins rays, head region and buccal cavity. Opaque of skin, hemorrhagic spots scattered on all parts of infested fishes specially perianal, caudal and pectoral region, mechanical damage of skin, erosion, sometimes reach ulceration of skin were observed. Infested fishes were showed gasping of air and accumulated around the water inlet (High current water). The postmortem finding showed presence of large number of parasitic crustaceans on the body surface, also occurred in oral cavity and under gills cover. In some cases, the gills were pale with brown focci look like marbling appearance, pale liver, congested spleen and kidney. Other cases showed congested liver and enlarged gall bladder and distended with bile. The result of bacteriological examination revealed the isolation of Vibrio alginolyticus and Vibrio species. V. alginolyticus was isolated with 40% from infested fishes with Caligus. V. alginolyticus was isolated with high percent from necrotic skin, gills, liver and kidney respectively while in low percent from spleen and blood. The pathogenicity of isolated V. alginolyticus was done and recorded. The result of antibiogram revealed that, florefenicol and ciproflox were highly effective against V. alginolyticus. The parasitological examination revealed that the crustacean parasites were identified as copepods of Caligus curtus, the total prevalence of infestation was 100% and the mean number of individuals per host was thirty five. The histopathological finding of infested skin and gills of infested Mugil cephalus were studied. The trial of treatment by using Butox ® 50 in dose 0.2 ml /L (10 ppm/L) as bath for 5 minutes gave effective control of Caligus and should be repeated after 7th day of first application.
