Granulomas caused by Mycobacterium sp. in farmed Turbot Scopthalmus maximus (Linnaeus, 1758)

Abstract

Turbot, Scophthlalmus maximus, is a pleuronectiform fish that occurs in the northeast Atlantic along the European coast and in the Mediterranean Sea, and is produced in fish farms since the last quarter of the twentieth century. During a survey conducted in a turbot fish farm, nodular formations were occasionally observed in several organs, especially in the kidney and in the spleen. Microscopic observations showed that these nodules contained acid-fast bacilli. Molecular identification of the isolated bacteria revealed the Mycobacterium genus. Although no abnormal mortalities were evident morbidity was observed. The normal development and welfare of infected fish decrease and the condition factor, the haematocrit and haemoglobin concentration in blood decreases significantly with the increase of nodule abundance.

Short-Term Alternate Feeding between Terrestrially Sourced Oil- and Fish Oil-Based Diets Modulates the Intestinal Microecology of Juvenile Turbot

“…Mycobacterium is a Gram-positive, acid-resistant, and inactive bacterium. It causes chronic diseases in many cultured and wild fish, such as turbot, European seabass (Dicentratrchus labrax), and striped bass (Morone saxatalis) [47][48][49]. The high abundance of Mycobacterium in the SO/FO group may be due to the presence of phytosterols in the soybean oil, which can be used by Mycobacterium [50].…”