Euclinostomum heterostomum infection in guppies Poecilia reticulata cultured in Southern Thailand.

During April to June 2009 and February 2010 to February 2011, numerous digenetic trematode metacercariae were observed embedded in the muscles of guppies Poecilia reticulata cultured at Kidchakan Supamattaya Aquatic Animal Health Research Center, Songkhla, southern Thailand. A total of 424 guppies were examined to identify the parasite and to study its pathogenicity. Based on conventional parasitological techniques, the parasitic digenean found in the guppies was identified as Euclinostomum heterostomum Rudolphi, 1809. Histological analysis revealed numerous metacercariae embedded in the fish muscle. A life cycle study indicated that the snail Indoplanorbis exustus was the first intermediate host, with the guppies serving as the second intermediate host. No E. heterostomum metacercariae were found in cohabited fish species, giant sailfin molly Poecilia velifera or platy Xiphophorus maculatus, which indicated that the guppy was the only suitable fish host present.