First Record of Spironucleus vortens Parasite in the Common Angelfish Pterophyllum scalare in Syria

Abstract

Parasitic infections in ornamental fish are an increasing concern in freshwater aquaculture because they affect fish health, biodiversity, and the market value of infected fish, causing economic losses in the ornamental fish trade. This study reports the first confirmed record of Spironucleus vortens in the common angelfish Pterophyllum scalare in Syria.

Twenty fish, both clinically affected and apparently asymptomatic, were collected from a private ornamental farm in rural Latakia during five seasonal sampling campaigns
 (2023–2024). Light microscopy (100×, 400×, 600×) revealed trophozoites in the posterior intestine and in head lesions of severely infected fish.

The parasite showed a pear-shaped, bilaterally symmetrical body, two anterior nuclei, eight flagella (six anterior, two posterior), and active spiral motility. Identification relied on classical morphological criteria, assigning the parasite to the order Diplomonadida and the family Hexamitidae. This first Syrian record adds to regional parasitological data and underlines the need to monitor intestinal flagellates in sensitive ornamental species, particularly under closed culture conditions where they may contribute to hole-in-the-head disease.