Prevalence and Morphological Characterization of Hysterothylacium sp. (Nematoda: Raphidascarididae) Recovered from Infected Organs of Lizardfish (Saurida undosquamis)

Aims: This study was aimed to determine the prevalence and morphological features of Hysterothylacium species from different infected organs in lizardfish in Misurata, Libya.

Place and Duration of Study: The study was carried out at Misurata University, Misurata, Libya, between June 2018 and May 2019.

Methodology: 192 specimens of the Saurida undosquamis were collected from the local market of Misurata city in Libya. Lizardfishes were examined only for Hysterothylacium species. After collection, Nematodes were identified by the naked eye or by using the lens, were isolated in a sterile container containing normal saline, and were washed several times with normal saline to remove any attached mucus.

Results: The prevalence rate of Nematoda helminths in examined fish Saurida undosquamis, was high. Based on the morphological and morphometric characterization, only one Nematode species (Hysterothylacium sp.) was isolated. Of the total fish examined, 189 (98.4%) were infected with Hysterothylacium sp. The density of Hysterothylacium sp. was around 2557, and they were collected from the stomach, anterior and posterior parts of the intestine, liver, and muscles in all seasons, but gills only in autumn and winter. The high-density rate in spring (823), followed by winter (757), with non-significant differences between density rates in all seasons (P > 0.05).

Conclusion: This study found a high infection rate with Hysterothylacium sp. in the examined Saurida undosquamis. This nematode species is commonly recovered in marine fish and is probably negligible concern for public health.