Hiding abnormally
Fish hides behind rocks or suchlike, appearing seldom if ever.
Bacterial infection by Nocardia spp. Mostly identified as Nocardia seriolae.
Virulent disease, difficult to treat succesfully. Strict hygiene is essential for prevention and cure of this disease.
From DOI: 10.1111/j.1365-2672.2006.02872.x