Fig. 1. Black lesions in the trunk muscle of longtooth grouper.

Parasite	Microsporidium sp.
Taxonomy	Microspora, Microsporea
Host	Longtooth grouper (Epinephelus bruneus)
Infection site	Trunk muscle
Clinical sign	Black fiber-like lesions (several mm in length) are observed in the trunk muscle (Fig. 1).
Parasitology	Many bean-shaped spores were formed inside the lesions.
Pathology	The black lesions are considered to be degenerated parasites with melanin deposition. At this stage, most of spores are hard to be detected.
Health hazard	Since this parasite is not infectious to human, it is harmless in food hygiene.
Diagnosis	Check the spores by the wet-mount of cysts. The sample should be smeared and stained by Uvitex 2B followed by a fluorescent microscopic observation. The stained spores emit blue fluorescence under UV radiation.