CERATOMYXA SPP (PROTOZOA, MYXOSPOREA) INFECTIONS IN WILD AND CULTURED SEA BASS, DICENTRARCHUS-LABRAX, FROM THE SPANISH MEDITERRANEAN AREA

Ceratomyxa labracis and Ceratomyxa diplodae, parasitic in the gall bladder of wild and cultured Mediterranean sea bass (Dicentrarchus labrax L.) were studied. Prevalences were clearly higher in cultured fish, especially for C. labracis. Starvation seems to favour the appearance of ceratomyxosis. Infection varied seasonally, with maxima in winter and minima in summer, a pattern almost contrary to temperature. Prevalence of C. labracis decreased in older fish. No clear influence of host sex was observed, and the apparent negative association between the two Ceratomyxa spp. was not confirmed statistically. Different degrees of histopathological damage of the gall bladder were observed by light and electron microscopy, mainly consisting of vacuolation, deformation or even necrosis of epithelial cells, and thickening and inflammation of the subepithelial connective tissue. Trophozoites appeared frequently lining the epithelium, closely attached to the cell surface or even forming invaginations in it. The importance of ceratomyxosis for sea bass and the influence of culture and stress conditions are discussed. Copyright © 1993, Wiley Blackwell. All rights reserved