Occurrence of Ceratothoa capri (Trilles, 1964) in Pomatomus saltatrix (Linnaeus, 1766) in the Libyan Coasts

Ceratothoa is an important ectoparasite affecting many species of commercial fish. 40 individuals of wild bluefish, Pomatomus saltatrix (L, 1758), were collected during October and November 2022. One pullus Cetratothoa capri parasite was found inside the bluefish gill, P. saltatrix from the coasts of Libya, in the southern Mediterranean determination, the infection rate of the fish was 2.5%. This is the first study from Libya on the presence of C. capri in bluefish.

Pomatomus saltatrix L, 1766 (Perciformes, Pomatomidae) is considered one of the economically important commercial migratory fish in many countries of the world, which has decreased in its numbers in recent years (Kasim et al., 2009;Trilles & Öktener, 2009;and IUCN, 2015).It is considered one of the fish that has a wonderful taste and is expensive.It is locally called Al-Maghars fish, and its common name is the bluefish.It has a dark spot at the base of the pectoral fin, a large head, and a row of strong teeth in each jaw, silver or greygreenish in color on the dorsal side (Kasim et al., 2009).
There are little of studies on Ceratothoa species or on P. saltatrix from the Libyan coasts, including Abdulla and Howege (1989); Shakman et al. (2009); and Mahmoud et al. (2018).The present study aims to identify and describe for the first time a species of an ectoparasitic Cymothoid isopod, Ceratothoa capri in Pomatomus saltatrix gill, from the coasts of Libya.

Materials and Methods
The Bluefish, P. saltatrix was obtained from the western coast of Libya, which is located in North Africa and south of the Mediterranean.They were collected during October and November 2022 and transferred in a container containing crushed ice directly to the laboratory of the Zoology Department, Faculty of Science in University of Tripoli, where the surface of the fish body, pectoral, pelvic; also caudal fins, buccal cavity, and gills were examined to detect the presence of any crustacean ectoparasites that will be found.The parasite was kept in a container containing alcohol.Then was examined by a binocular microscope, and determined through the use of identification keys (Trilles, 1964;1972;and Horton, 2000).

Results and Discussion
A total of 40 Pomatomus saltatrix individuals were collected freshly from the mainland markets, one sample from 40 specimens (2.5%) was infected with a pullus parasitic isopod was found in the gill of the bluefish host species and belonged to the genus Ceratothoa.

Morphology
This study showed the presence of one individual of the parasite Ceratothoa capri in the pullus stage, 5 mm T.L, shown in Figure ( 1) inside the gill of the male bluefish host (Total length 25.2 cm and Total weight 145.3 g).

Body shape:
Elliptical, distinctly, the length is more than 1.5 times the width, smooth the dorsal side is dark and smooth (Fig. 2).

Cephalon:
Triangular in shape from the dorsal side, the cute lateral marigin transcend the well-distinct and large oval eyes (Fig. 3).

Pereonites:
The anterior side is sharp and straight, heading forward towards the anterior margin of the eyes.Pereonites 1-5 increase in length and width as we go to the posterior side, and its maximum expansion is at Pereonites5, then it gradually approaches and narrows from Pereonites 6-7.

Perepods:
Its length is about 1.7 times the width, and it contains a bulge on the proximal side of the Merus, there are no expansions of the merus.The carpus is a straight margin; expansions occur only at the lower edge of pereopods VI &VII (Fig. 4).

Pleonites:
The first is narrow, while the second to the fifth is narrow and rounded.The fifth is characterized as free because it does not overlap with Pleonites 4.

Pleotelson:
It is narrow, the posterior edge is angled, and has slightly convex lateral margins.In the dorsal part, there are submedial depressions.

E-5
ISSN (Print): 2413-5267 ISSN (Online): 2706-9966 According to Trilles (1964Trilles ( & 1972) ) C. capri was found in the gills, and in the bottom of the buccal cavity of Capros aper (Trilles).This agrees with the present study, where it was found in the gill.While this study differs from several studies that found infection with C. capri in the buccal cavity from the fish, including of the study of Kirkim et al. (2008); Innal and Kirkim (2012) for Boops boops and Spicara smaris; study of Kirkim et al. (2009) for Centracanthus cirrus; and Al-Zubaidy & Mhaisen (2013) showed the infection of Chelon macroleps; Başusta et al. (2017) was found the parasite-infected in Raja miraletus, which is considered elasmobranch fish.

Conclusion
Parasitism affects living organisms, where the parasite usually obtains its food by sucking the blood of the host, causing diseases and sometimes leading to death, and thus it affects the food chain, and causes damage to the ecosystem.Cymothoid has increased in recent decades in the eastern Mediterranean, exceeding 20 species; on the coasts of North Africa, 16 species have been identified from Algeria, 15 from Morocco, 11 from Tunisia, and from Egypt 4 species according to the literatures, while have been identified on the coast of Libya by Shakman et al. (2009) were recorded Anilocra frontalis, A. physodes, Nerocila bivittata, N. orbignyi, N. maculata, Ceratothoa parallela, C. oestroides and C. oxyrrhynchaena.Also, the C. paralella was identified by Mahmoud et al. (2018) in Boops boops.While the present study is considered the first record in Libya of the infection of P. saltatrix with the C. capri parasite.There are currently about 30 species belonging to the genus Ceratothoa, many studies describing C. capri and working to define it.Pomatomus saltatrix is considered one of the Teleostei, that exist in small quantities and their numbers are decreasing successively, and they have the problem of parasitism of one of the Cymothoids, as it was found in this study that it was infected in the gill region from the inside with pullus the C. capri.
The fishermen return fish lice (crustacean isopods) to the sea again as soon as they see this parasite on the fish, thus the life cycle of the parasite is repeated to infect the same species of fish or another, this action may be the main reason that I did not get the mature stage of the parasite, especially since the pullus of C. capri was 5 mm long and hidden at the base of the gill, it's hard to watch easily.SO, Fishermen must be alerted to the danger of in …………………………………… Faculty of Marine Resources, Alasmarya Islamic University, Libya.E-3 ISSN (Print): 2413-5267 ISSN (Online): 2706-9966 Superfamily: Cymothooidea Leach, 1814.Family: Cymothoidae Leach, 1814.Subfamily: Ceratothoinae Dana, 1852.Genus: Ceratothoa Dana, 1852.