~ 88 ~ International Journal of Fisheries and Aquatic Studies 2017; 5(3): 88-94 E-ISSN: 2347-5129 P-ISSN: 2394-0506 (ICV-Poland) Impact Value: 5.62 (GIF) Impact Factor: 0.549 IJFAS 2017; 5(3): 88-94 © 2017 IJFAS www.fisheriesjournal.com Received: 14-03-2017 Accepted: 15-04-2017 Ihab K Mohamed Department of Zoology, Faculty of Science, Ain Shams University, Cairo, Egypt Suzan E Ali Department of Environmental Research and Medical Malacology, Theodor Bilharz Research Institute, Giza, Egypt Nahed M Ismail Department of Environmental Research and Medical Malacology, Theodor Bilharz Research Institute, Giza, Egypt Correspondence Ihab K Mohamed Department of Zoology, Faculty of Science, Ain Shams University, Cairo, Egypt Impact of watercourse lining in Egypt on the gills of the Nile tilapia Oreochromis niloticus: Histopathological and biochemical study Ihab K Mohamed, Suzan E Ali and Nahed M Ismail Abstract The present study was aimed to investigate the impact of lining of the watercourses on histology and function of the gills of the tilapia fish. The investigated sites were divided according to the degree of the pollution into two study areas. The first study area was less polluted than the second one. Both areas were divided into two sites according the existence and the kind of the lining that they have. The study area 1 has site I: El-Bostan canal lined with cement and site II: unlined Nasser canal that has a sandy soil, sites I and II are in El-Beharia governorate. The study area 2 has site III: River Nile lined with rocks, in Giza governorate and site IV: unlined Ismailia Canal with a muddy soil, in Al-Qaluobia governorate. The microscopical examination showed presence of marked histopathological alterations of the gills of fish collected from the lined and the unlined sites. The severity of these changes ranged from mild ‒ as in the samples of the lined sites ‒ to severe in those of the unlined sites. These findings included atrophy and curling in the gill lamellae, interstitial odema, necrosis of the epithelial lining, rupture of the pillar cells and capillaries, telangiectasis and aneurism. The biochemical results revealed an increase of the values of urea and creatinine in the serum of the fish collected from the unlined, highly polluted study area. These biochemical changes may be attributed to the gill dysfunction that is due to the recorded histopathological alterations. Keywords: Lining of watercourse, Oreochromis niloticus, histopathology, gills, urea, creatinine, tilapia, Egyptian canals 1. Introduction The issue of water loss through irrigation systems has major impacts on the surface water supplies so, it needs management. Seepage loss could be effectively minimized by the use of an impervious medium as a canal lining between the porous soil and the water flow [1] . Lining of watercourses is one of the environmental modifications used in irrigation schemes to reduce the water loss. Also, it could reduce the bacterial growth and thus preserving the water with a good quality [2] . The water quality is one of the most important conditions that are controlling life in the aquatic ecosystems. The quality of water and the well-being of the aquacultures are interconnected and directly proportional [3] . Thus, the maintenance of good water quality is essential for both survival and optimum growth of the aquatic fish [4] . Also, the diversity, distribution and the population size as well as the state of health in fishes are affected mainly by the water quality [5] . The fluctuations, even slight, in any of the water parameters, severely affect the dwelling of fish [6] . Fish are one of the most indicative species in freshwater systems because they respond with great sensitivity to any change of their surroundings. Fish are usually considered as organisms of choice for assessing the effects of environmental changes and they are used as bio-indicators in monitoring the water pollution of the aquatic ecosystem [7] . River Nile is the main water source for Egypt. It constitutes over 98 % of the fresh water resources. Many studies proved that the polluted water caused a severe damage to the cells and different tissue of the fish inhabiting these places [8, 9] . It is believed that the gills of fish exposed to irritants are of the most important organs that are highly affected [10-13] . The River Nile is receiving huge amounts of pollutants including the agricultural and domestic sewage [14] as well as the industrial wastes [15] which find their way into the river and its branches. So, the objective of the present study is to investigate the impact of lining of water bodies on the gills of the Nile tilapia; Oreochromis niloticus (Linnaeus, 1766).