T HE objective of this study was recorded the most prevailing bacterial agents which spreads in the cultured fish in Ismailia province, Eastern Egypt. This study was carried out on 1080 premature fish. 360 Dicentrarchus labrax (225±25 g) and 360 Sparus aurata (150±25 g), and 360 Mugil cephalus (125±25). The examined fishes showed exophthalmia, hemorrhagic area on the skin, around the buccal cavity, head, and on the base of the fines, ulcers varied in their degrees, dark colour, and respiratory signs. The recorded postmortem lesions were septicemic signs with enlargement and congestion of the liver and spleen with distended gall bladder. With the presence of serous to hemorrhagic ascetic fluid, the stomach and intestines displayed congestion, thickening, and inflammation of their walls. The total prevalence of bacterial infection in examined premature fishes was 27.68%. The highest percentage was in D. labrax at 38.88%, followed by S. aurata at 27.22%, and the lowest percentage in M. cephalus at 16.94%. The most prevailing bacterial agents were Vibrio spp and Pseudomonas spp.

T HE aim of this study was to assess the impact of major parasitic crustacean invasions on farmed marine fish in Ismailia Province, Suez Canal Region, Egypt. A total of 540 premature, 180 Dicentrarchus labrax (225 ± 25 g), 180 Sparus aurata (150 ± 25 g) and 180 Mugil cephalus (125 ± 25 g) were collected from assimilatory ponds in Ismailia farms. They were investigated for crustacean infestation between May 2021 and August 2022. Infected fish were characterized by respiratory symptoms, reduced food intake and growth rate, abrasion, erosion, and ulcers of varying sizes. The overall prevalence in untreated premature animals studied was 53.44%, D. labrax 63.87%, S. aurata 53.60%, and M. cephalus 36.92%, respectively. While, the prevailing of infestations after treating the same fish with 5% of microalgae (Amphora spp and Nanochloropsis spp ) that added to feed were 21.48 % (33.88, 23.61, and 16.94% for D. labrax, S. aurata, and M. cephalus, respectively). The parasite species detected were the crustaceans Lernanthropus spp. and Caligus spp. from D. labrax, M. cephalus, and S. aurata. Histopathological alterations were recorded in the gills and musculature. Microalgae played an important role in the spread of fish diseases in the studied fish.