الفهرس 
Branchial cavity and gills examinationOnly 14 pages are availabe for public view
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Abstract
Fishes are one of the most important groups of vertebrates that
serve as food for human. They possess a great nutritional,
economic, environmental and social values. In addition, fishes
provide employment for great numbers of people in the world
(Lynch et al., 2016). Also, fish considered as an essential source of
proteins available for humans and other animals in the tropic
countries. According to the Food and Agriculture Organization
(FAO) of the United Nations, fishes represent more than 40% of
the protein diet of two-third of the global population. In addition,
fishes are one of the most effective ways to provide protein with
relatively competing prices, as other animal's proteins are so
expensive (Sabri et al., 2009).
Egypt has many sources of fishes; the Mediterranean Sea, the Red
Sea in addition to the Nile with several lakes and fish farms. Huge
loss of production in aquaculture is occurring because of many
reasons. Among these reasons, diseases which are the most serious
constraints that cause damage to fish production (Assefa and
Abunna, 2018). Parasitic diseases considered one of the most
important problems facing fish breeding and production at
commercial scales (Abdel-Ghaffar et al., 2009). Parasitic diseases
have serious impact on the fish as they cause mortality, low growth
rate, lower food conversion rates and decreased marketability as
well as it may has zoonotic threats to human consumers (Elsheikha
and Elshazly, 2008).
Infectious and parasitic diseases of fish cultured under
controlled conditions are significant factors restrictive the
development of fish aquaculture (Bernad et al., 2017). Also, the
study of prevalence of parasites in fishes is necessary and important
to decrease their effects on fish population to improve the stocks of
valuable commercial fisheries in the natural waters and to the
possibility of fish acclimatization in new sites or localities
(Shul′man, 1961).
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Rodger (2016) postulated that the management and control
of infectious disease are the main hurdles to sustainable finfish
aquaculture in many regions. The study of fish parasites is therefore
attractive for many parasitologists, since they not only cause
injuries or even death to the fish (Davis et al., 1961), but also do
some human health problems (Bernad et al., 2017).
In Egypt, parasitic diseases represent about 80% of fish
disease (Ghoneim et al., 2015). Thus, the contribution to the
knowledge of fish parasitic diseases is a prerequisite for the rapid
and correct diagnosis of the disease agent of epizootics. Early
diagnosis can lead to preventive measure, which is the best way to
reduce outbreaks of disease (Bylund et al., 1980). Following this
concept, the present study was therefore suggested to survey the
parasites infecting fishes in Lake Wadi El- Raiyan and Bahr
Youssef in Fayoum Governorate.
Area of study
1- Lake Wadi El- Rayan
The valley of Wadi El- Rayan is an area of 1,759 square kilometers,
113 square kilometers of which are the dominating water body of
the Wadi El-Rayan lakes. It is located about 65 km southwest of
Fayoum city and 80 km west of the Nile River. The source of water
in this lake is agricultural and municipal drainage from the El
Fayoum province. In 1973, Wadi El-Rayan was connected with the
agricultural wastewater drainage system of the Fayuom province
and received water that exceeded the capacity of Lake Qarun
(Mohamed et al., 2015).
2 – Bahr Youssef
Bahr Youssef is a canal which connects the Nile River with
Fayoum city in Egypt. It is about 92 km southwest of Cairo. El-
Fayoum gets its water supply exclusively from Bahr Yusuf, a side
branch of the Nile which leaves the river in the area of Assiut and
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enters Fayoum at the Lahun Gap (Römer, 2017). Bahr Youssef
Canal runs from Ibrahimiya canal of the Nile River at Dirout city
that cross Assiut, Minya and Beni Suef Governorates, before
entering Fayoum (Bream et al., 2017). Bahr Youssef divided into
sub-canals among Fayoum and splits into eight channels (Hewison,
2008). El-Fayoum receives fresh water from Bahr Youssef with a
share of irrigation water amounts to approximately 2.5 (bcm) yearly
(El- Zieny and Effat, 2019).