Lake Temsah is the end point where some municipal, agricultural and industrial wastewaters are discharged. The lake is connected to the Suez Canal where large volumes of petroleum oil are passed from producing countries in the Arab Gulf to Europe and North America. The lake is the main source of fish for the area of Ismailia and a recreational site where the tourism industry thrives. Recently, numerous complaints have been made about the level of pollution in the lake which affects to a significant extent fishing and tourism industries. In the present study, residues of some chlorinated hydrocarbon pesticides, polycyclic aromatic hydrocarbons and polychlorinated biphenyls were monitored in some of the lake's organisms. Mullet (Mugil cephalus, usually living in the water column), crab (Lupa pelagcus, an intertidal organism) and a bivalve (Ruditapes decussata, a benthic sedentary organism) were selected as representatives of various strata of the lake ecosystem. Residues of an endosulfan, DDE, Dieldrin, heptachlor epoxide and Dicofol were detected. Aroclor residues were not seen. Endosulfan had the highest detected concentration of all organochlorines: concentrations were 24.1, 52.3, 124.8, and 65.6 µg kg -1 in fish skin, fish gills, fish muscles and bivalves respectively. DDE was the most frequent detected organochlorine, detected in all samples, while Dieldrin was only detected in bivalves and crab. The concentration of polycyclic aromatic hydrocarbons was lowest in fish skin, 2.7 µg kg -1 , and highest in bivalves, 48.9 µg kg -1 . Fluorine and anthracene were the most frequently detected polycyclic aromatic hydrocarbons compounds, while acenaphthene was the least detected. The highest concentrations of organochlorines and polycyclic aromatic hydrocarbons, 108 and 48.9 µg kg -1 , respectively, were detected in bivalves. Bivalves also had the widest spectrum of detected organochlorines and polycyclic aromatic hydrocarbons. All tested organisms showed a higher ability to accumulate organochlorines in comparison to polycyclic aromatic hydrocarbons. Results also showed some indications that factors other than fat content may have some influence on the accumulation of persistent contaminants in biological tissues.

Because of the difficulties facing the treatment of flavobacteriosis, this study aimed to evaluate kaolin (a type of clay) for the prevention of such disease in Oreochromis niloticus. Addition of kaolin at rate of 1 g/L, to the water aquaria, 5 min prior the challenge of O. niloticus, protected the fish against columnaris disease (100%) and improved survival (93.7%) as compared to untreated fish (50 and 66.7%, respectively). The re-isolated strain from untreated challenged fish confirmed through a pair of 16S RNA gene-based PCR primers specific for F.columnare and produced unique and clear PCR bands of the expected size (675 base pair).

A total number 200 different marine fish species represented as 100 Elsarah (Nemipterus japonicus ) and 100 Mias (Pomatomus saltatrix L.) were collected seasonally from Suez and Ismailia provinces respectively . The infested marine fishes revealed no pathognomonic signs.They were investigated for detection of Isopoda parasites. It was revealed that 50% of the examined marine fishes was infested.The detected species were Irona nanodies from Nemipterus japonicus with a prevalence 60% , and Lironeca ovalis from Pomatomus saltatrix L with a prevalence 40%.The histopathological alterations were recorded and discussed.The secondary bacterial invasion was manifested by the isolation of Pseudomonas aeruginosa where it was experimentally infected into Tilapia zillii and reisolated again.

A total of 120 Oreochromis niloticus were collected randomly and seasonally. Fish were examined freshly from western lagoon (Berket El-Siadin) which is branch from Lake Temsah in Ismailia governorate .the result revealed that post mortem lesions in liver was in the form of pale and enlargement in some cases, while in other cases showed variable degrees of congestion and hemorrhage spots. Spleen was dark in color and enlarged, kidneys appeared congested and the gall bladder was full and distended. The periodic difference of heavy metals concentration based on the data of water samples gathered from the same lagoon showed the following manner as: summer > autumn >winter. The results revealed the presence of metals in the following order: Fe > Cu >Pb > Zn > Cd. The concentration of heavy metals in fish liver, gills and musculature were always higher than of the water, indicating the bioaccumulation. The highest concentration of heavy metals in water and fish tissue was associated with the lowest RBCs count, Hb, PCV, leukocytosis, hypoproteinemia and elevation in serum AST and ALT levels than normal. So, there is accumulating evidence that some heavy metals are immunosuppressive and fish may be more exposed to disease.

The present study was planned to investigate the clinicoplathological and histopathological changes on the blood of catfish (Clarias gariepinus) infected with Pseudomonas florescence. A total number of 240 catfish were collected from Ismailia channel and subdivided to 4 groups 60 for each: the control group, infected group, β-glucan group and β-glucan infected group. The blood samples were taken at 1, 3 and 5 weeks for hematological and biochemical examinations. Tissue samples from spleen, liver, kidney and gills were taken for histopathological techniques. The hematological results revealed significant decrease of RBCs count, Hb concentration and PCV% with significant increase of T.L.C, heterophils and lymphocytes of the infected group compared to the control group. The β-glucan groups showed significant increase of RBCs count, Hb and PCV% with significant increase of T.L.C, heterophils, lymphocytes and monocytes. Serum biochemical results showed marked elevation in ALT, AST, urea, creatinine, uric acid and glucose of the infected group. While, βglucan improved the liver function, kidney function tests and glucose before and after the infection compared to the control group. The challenge test revealed a significant lower mortality percentage in the group received β-glucan supplemented diets. Histopathologically, marked degenerative changes and necrosis were evident in the infected group. While, β-glucan groups showed hyperactivity of melenomacrophage centers of haemopiotic organs. It could be concluded that β-glucan acts as a dietary supplement.