Research study on the frequency and pathogenicity of the "black spot disease" in the finfish inhabiting the Danube Delta area.

The study was focused on assessing the aetiology, frequency and the morphopatological characteristics of the “black spot disease” in the cyprinids inhabiting some aquatic complexes within the Danube Delta area. This research was conducted between 2003 and 2008, as a cross-sectional survey. Following the parasitological examinations, it resulted that two trematod species were involved in “the black spot disease”, Posthodiplostomum cuticola and Rossicotrema donicum . The disease was found in hypophthalmichthys molitrix and perca fluviatilis captured from Dunavat-Dranov and Razim-Sinoie, scardinius erythrophthalmus gathered from the Gorgova-Uzlina lakes, and in vimba vimba captured from the Sontea-Fortuna lakes. The recorded disease prevalence in S. erythrophthalmus was of 26.56%, whereas in H. molitrix it was of 30.26% in the Dunavat-Dranov lakes and 28.12% in the Razim-Sinoie lakes. In what it concerns the pathogenicity of the disease, it is worth it mentioning that where muscle localizations of the metacercariae occurred, isolated muscle tissue melanization (pigmentation) was noticed. Likewise, the size and shape of the spots varied with the fish species studied.