An epizootic in juvenile turbol reared on a farm located in the Rla de Vigo, Galicia, Northwest Spain, is described. The diseased turbot did not display unusual swimming behaviour; the external signs of the disease were abdominal distension and haemorrhagie in the peritoneal cavity. Microbiological analysis of the diseased fish revealed the presenee, in pure culture in all the organs and lesions examined, of a bacterium whieh was characterized biochemically as Vibrio splendidus biotype 1. The virulenee tests showed that the V. splendidus biotype 1 isolate was pathogenic for rainbow trout (LD30

A method for studying the efficacy of sulfadiazine as a marker to estimate feed intake is presented. Feeding studies were carried out with two species, rainbow trout as a freshwater fish model and gilthead sea bream as a marine fish model, using two temperatures and two sizes of juveniles. The study showed the different feeding behaviour observed in both species, depending on the temperature and the number of days feeding the particles with sulfadiazine, and confirmed a dominant-subordinate behaviour especially in the case of gilthead sea bream juveniles.