Microsporidian infection in lizardfish, Saurida undosquamis of Persian Gulf

Lizardfish is one of the economically important fishes of Persian Gulf. In recent years, white, ellipsoid, round or elongated nodules were found in body cavity of this fish species which in preliminary microscopic examination were recognized as microsporidia. To determine the approximate prevalence rate of microsporidian infection and to establish its taxonomic position, 50 lizardfish were bought from the local markets of Ahvaz city (the center of Khozestan province – Iran) and transferred to the laboratory for parasitological examination. In the laboratory, internal organs including liver, kidneys, spleen, intestines, gonads and muscles were examined grossly and microscopically for the microsporidian infection using wet and dry smear (stained with Giemsa). Histopathological sections were prepared from the cysts of infected fishes and stained with haematoxylin and eosin to see the arrangement of the spores within the cysts. Some of these small cysts were sampled and fixed in 3% glutaraldehyde for electron microscopic study. According to the results, the total infection rate was 44%. The infection rate in the peritoneum, stomach, gonads, intestine, spleen, muscles and liver were 16, 2, 4, 8, 2, 10 and 2%, respectively. The cysts were mostly ovoid in shape with mean size of 4.3 ± 1.8 mm (0.8 to 10 mm). The spores were ovoid and uninucleate with mean diameter of 2.4 × 1.3 μm. Polar tube coiled between six and eight time, in one row. According to the histopathology and light and electron microscopic studies, the parasite was recognized as Glugea sp .