| Pathogen | Chromatiaceae bacterium |
|---|---|
| Taxonomy | Bacteria, Proteobacteria, Chromatiales |
| Host | Flathead mullet (Mugil cephalus) |
| Clinical sign | A dead flathead mullet looks like red paint on (Fig. 1). |
| Bacteriology | Pink colored bacteria (2×3-6 mm) are proliferated on the surface of dead fish. The bacteria are motile and pleomorphic, e. g. spherical to cylindrical in shape. Several to ten large granules are observed inside the cell (Fig. 2). The bacterium is morphologically similar to Chromatium minus, a Chromatiaceae photosynthetic bacterium. |
| Pathology | No report |
| Health hazard | Since this bacterium is not infectious to human, it is harmless in food hygiene. |
| Diagnosis | Observe the bacteria from the body surface under a light microscope. |
| Other information | This disease occurred in the river where dissolved oxygen is almost absent due to the low rainfall and the water pollution by the release of sewage effluent. Several hundreds of flathead mullet died, and a part of them exhibited red color on the body surface. Similar color changes were also observed on the surface of the dead branches in the bottom of the river. Such phenomena ceased after the enough rainfall (Momoyama and Tensha, 2006). |
| References | Momoyama, K. and K. Tensha (2006): Ugly-looking parasitic infections and
other abnormalities of wild fish and shellfish caught in the coastal or
inland waters around or in Yamaguchi Prefecture. Bull. Yamaguchi Pref. Fish. Res. Ctr.,
4, 143-161. (In Japanese) |
Fig. 1. Diseased flathead mullet.
Fig. 2. Bacteria from the lesions of mullet.