Systemic Granulomatosis in the Meagre Argyrosomus regius: Fishing for a Plausible Etiology

Meagre (Argyrosomus regius) is a fast-growing species used in aquaculture, but it faces significant challenges from Systemic Granulomatosis (SG), a disease marked by granulomas in various internal organs. This study investigated the possible link between Mycobacterium spp. and SG in 34 seemingly healthy meagre from a Sardinian aquaculture facility. Granulomas were identified in 91% of the fish. Several diagnostic methods, including acid-fast staining, microbiology, PCR, and in situ hybridization, were employed. While M. chelonae was detected in a low percentage through PCR (13%), no evidence suggested its role in SG onset.