Abstract
The present work was aimed to investigate two fish species; Sea bream (Sparus auratus and Tilapia zilli during summer and winter season to isopod parasitism and recorded of the parameters followed parasitism.
The present work based on 300 fish samples representing two fish species; Sea bream (Sparus auratus and Tilapia zilli 150 samples from each species in different seasons) which were captured during summer (June, July, August) and winter season (September, October, November) 2023 in the fifty ponds with nearly similar size 2 and half Fadden (10500 cubic meter of water capacity) for each pond of private farm at Mothalas El-Dibba, Domeitta governorate, Egypt.
The results cleared that, the clinical picture in the naturally infested fishes Sea bream and Tilapia zilli were opened mouth and degeneration of the gill filaments, presence of juvenile’s parasite in the gill chamber or buccal cavity of different infested. The data of water quality in summer and winter season during the isopoda infestation in both sea bream and Tilapia zilli , the level of temperature, Unionized- ammonia (NH3), sulfate (H2S) and nitrite were higher in summer season than the winter season than the permissible limits of these parameters mentioned in the different references refers in the ideal water quality in both cultured sea bream and Tilapia zilli. In general the all parameters of the water quality were in the higher levels than reported in the summer season. The higher rate of infestation with isopods was recorded during winter (80%) while during summer (62.86%). There was a significant value between the rate of isopod infestation and seasons. The glutathione, super peroxidase, catalase level ranged from the higher level in non-infested sea bream and Tilapia zilli fish by isopoda than the infested one.
The results concluded that, the isopoda infestation of sea bream and Tilapia zilli fish resulted in significant changes emerged in the hematological (RBC, Hb, Ht), and differential leucocytic count as well as innate immune (cortisol, lysozyme and antioxidants such as Glutathione, Super oxide dismutase, Catalase) parameters of the sea bream and Tilapia zilli fish parasitized with isopoda more than non-infested. Deltamethrin was effective against isopoda without induce any toxicity. Thus, a continuous application of the treatment is required to maintain levels that are toxic to the parasite

Key words: Isopoda - Cultured fish - Sea bream - Tilapia zilli -treatment