Insight into the correlation between parasitic infestation and heavy metal concentrations in tilapia species inhabiting Lake Nasser, Egypt

Abstract

Tilapia are commercially important freshwater fish within the family Cichlidae. Tilapia are distributed worldwide and comprise the predominant fish species in Lake Nasser, Egypt, producing 15,433 tons annually (GAFRD, 2018). The name tilapia comes from the African Bushman word for fish (Trewavas, 1982). Tilapia has been dubbed 'the aquatic chicken' due to favourable production characteristics such as adaptability to various environmental conditions, rapid growth and reproduction in captivity, feeding on low trophic levels, resistance to disease, high-quality meat and good marketability (El-Sayed, 2006).Fish parasitic diseases constitute one of the greatest challenges confronting fisheries in Egypt and around the world. Most of the tilapia in Lake Nasser harbour macroscopic trematodes and nematodes, which infest the head and abdominal cavity and cause concern among

Molecular characterization of zoonotic anisakid Contracaecum spp. larvae in some fish species from Lake Nasser, Egypt

“…infection prevalence and intensity was consistent with Barson (2004); Sorour and Hamouda (2019), who found no seasonal variation in the prevalence of Contracaecum infection in Clarias gariepinus from Zimbabwe and Egypt respectively. These macroscopic parasites have high prevalence and high mean intensities in the examined fish species which reduce the marketability of infected fish and lead to serious economic losses as reported by Ezzat et al (2012); Hamouda and Abd Alkareem (2021); Sorour and Hamouda (2019); Younis et al (2017). Contracaecum third larval stage prevalence may be more or lower than in previous studies, which could be attributed to changes in the environment's biotic and abiotic elements during the time of these investigations (Lima et al, 2019).…”

Characterization of Clinostomum cutaneum and Clinostomum phalacrocoracis in tilapia species of Aswan Governorate, Egypt: A morphological, molecular and histopathological study

“…C. cutaneum was found in two forms (free and/or encysted) in cultured tilapia, while C. phalacrocoracis was found in encysted form in all tilapia species, indicating that each parasitic species had its own response and adaptive mechanism to host microenvironments (Echi et al, 2012;Shareef & Abidi, 2012). The presence of these metacercariae on the fish's skin and branchial cavity causes consumers to avoid the fish out of fear of the macroscopic parasites, resulting in economic losses (Echi et al, 2012;Ezzat et al, 2012;Hamouda &Abd Alkareem, 2021).…”

“…Additionally, we identified the parasite's free form in cultured fish, which is more aggressive than the encysted Clinical and post-mortem examinations of clinostomatid-infected fish are predictable due to the larval penetration and feeding activities of Clinostomum spp. and the cysteine proteases secretion; these parasites' excretory/secretory products degrade a significant amount of infected fish proteins (Hamouda & Abd Alkareem, 2021;Rizvi et al, 2010;Shareef & Abidi, 2012). Excess mucus was observed in infected gills, which may be the fish's protective mechanism against the vexing parasites (Hamouda et al, 2018).…”

“…The two detected clinostomatids predominate all year in the lake's tilapia species, which could be due to the complicated, multihost life cycle, in which piscivorous birds act as final hosts and snails act as first intermediate hosts, which is present in Lake Nasser all year; additionally, the development of fish trematodes is successful in the non-disrupted lake ecosystem (Hamouda, 2019;Hamouda & Abd Alkareem, 2021;Hamouda et al, 2018;Shareef & Abidi, 2012).…”

“…As a result, in this study, we first combine morphological and molecular techniques to identify clinostomatids infecting cultured and wild tilapia species in Aswan Governorate, Egypt. The development of effective strategies and proactive measures for these parasitic diseases is aided by definitive diagnosis.Clinostomatids infect a wide variety of fish species around the world including about 13 families and 77 fish species indicating low host specificity, but interestingly, in Egypt only cichlids are infected with these parasites(El-Naffar et al, 1983;El-Shahawy et al, 2017;Ezzat et al, 2012;Hamouda & Abd Alkareem, 2021;Hefnawy et al, 2019; Li et al, 2018;Mahmoud et al, 2014;Menconi et al, 2020;Montes et al, 2020;Saoud & Wannas, 1984;Simsek et al, 2018;Taher, 2009), as confirmed by this study.In Egypt, several authors reported yellow grub disease in tilapia species caused by C. phalacrocoracis, C. complanatum, C. tilapiae and Clinostomum spp. metacercariae infections, but no one reported C. cutaneum.…”