Hepatoxylon trichiuri (Cestoda: Trypanorhyncha) plerocercoids in cage-reared northern bluefin tuna, Thunnus thynnus (Osteichthyes: Scombridae)
Northern bluefin tuna (Thunnus thynnus) were caught by purse seine boats and brought to a farm for a rearing cycle of 1.5 years. Mortalities occurred in the first weeks of acclimatization at the facility. Parasitological examination revealed plerocercoids of the cestode Hepatoxylon trichiuri embedded in the stomach mucosa. The larvae were found in 28.4% of the fish and the mean abundance was 3.12 per fish. Histopathology revealed disseminated erosion at the site of attachment, atrophy of fundic glands, lymphocytic migration, and hyperplasia of connective tissue in the lamina propria. These symptoms, however, together with the parasite abundance, could not have triggered the mortalities. This is the first record of this parasite in northern bluefin tuna.
Digenea of Adriatic cage-reared northern bluefin tuna (Thunnus thynnus thynnus)
Cage rearing of northern bluefin tuna (Thunnus thynnus thynnus) in the Adriatic Sea is a relatively novel branch of aquaculture, with scarce literature on fish pathologies. In this study, viscera and gills of 52 specimens of 13 kg tuna showed an interesting composition of digenean parasitofauna. Most abundant and prevalent were the members of the Didymozoidae family Coeliodidymocystis abdominalis, Didymocystis wedli, Platocystis alalongae, Koellikerioides internogastricus, Koellikerioides intestinalis and Koellikerioides apicalis, isolated from various tissues. Ventricular, kidney and gill tissues showed disseminated granulomas, presumed to be the eggs of the blood trematode Cardicola forsteri, however no adult forms were found. This is the first report on tuna digenean parasitofauna in the Adriatic Sea.
A survey of didymozoid trematodes of the barracuda Sphyraena obtusata from Kuwait Bay.
Examination of 120 yellow-finned barracudas, Sphyraena obtusata, from Kuwait Bay revealed 8 species of didymozoid trematodes encapsulated in pairs in the tissues. Four species of the didymozoids, Allodidymozoon operculare, Didymocylindrus sp., Didymocystis sp., and Didymocystoides sp., were found in the head region, 3 species, Didymozoon tetragynae, Lepidodidymozoon sinicum and Platocystoides polyaster, in external surfaces and 1 species, Allodidymozoon sp., in stomach wall. The didymozoid species collected constitute new geographic distribution records and occurrence of D. tetragynae and L. sinicum are new host records.