Prevalence of Ceratothoa oestroides (RISSO, 1826), a cymothoid isopode parasite, in cultured sea bass Dicentrarchus labrax L. on two farms in middle Adriatic Sea

Abstract

            During the spring months on two finfish facilities in island Kornati aquatory, growth retardation, emaciation and 10 % mortality of sea bass fingerlings was noticed, even all zooprofilactic and nutritional measures were carefully conducted.

            From the buccal cavity of obvious kahectic and anorexic animals, a cymothoid isopode, Ceratothoa oestroides, was isolated and identified. The identification was followed on the basis of TRILLES’ studies.

           The prevalence of infection and some morphometric parameters of the host and the parasite were measured and statistically analyzed.

           Both farms had almost one third of sampled fish infected (25,6 and 27,5 % respectively). The results showed statistically significant decrease in total body weight of infected fish versus uninfected ones (17,3 and 66,7 %  respectively).

          The parasite, even nonspecific and widely distributed in all Adriatic, seams to cause major damage in young categories of sea bass, and it's more frequent than in a sea bream' fingerlings (Sparus aurata, L.), reared in the same facility, what could be explained with fingerlings' preferences and feeding habits. Older animals are rarely susceptible to the infection, depending however, on zoo-technical conditions on the farm.