Abstract
The present study aimed to isolate vibrio species from fresh and marine water fish responsible for summer mortality syndrome affecting Cage- cultured grouper species fish (Epinephelus aneus; Epinephelus guaza; Epinephelus alexandrines and Epinephelus caninus) and Lout fish (Argyrosomus regius) farms in Egypt.
A total of 250 fish of each species of grouper species fish (E.aneus; E.guaza; E.alexandrines and E.caninus) and Lout fish (Argyrosomus regius) were collected at different times. The fish samples were collected at summer and autumn seasons. The fish samples were 25 from each species in each season. Clinically diseased fish were collected live then rinsed with sterile water and packed in a sterile polystyrene bag. Collected samples were immediately transported in an icebox to the private fish diseases Lab, Alexandria branch. Grouper fish weight between (500 - 1000) g and Lout fish weight (4 - 4.5) Kg. The collected fish samples were submitted directly to the lab for clinical and bacteriological examination.
The results cleared that, after the clonical signs, post-mortem examination, isolation and identification on different media and molecular identification (PCR) of the isolated bacteria the main bacteria isolated from Grouper and lout were V. alginolyticus and V. parahaemolyticus.
This study concluded that, the Multi stress factors are responsible for summer mortality syndrome affecting cultured grouper species fish (Epinephelus aneus; Epinephelus guaza; Epinephelus alexandrines and Epinephelus caninus) and Lout fish (Argyrosomus regius) in Egypt; thermal stress associated with heatwaves is the main predisposing factor. Co-infections are very common in nature and occur when Cage- cultured grouper species fish (E.aneus; E.guaza; E.alexandrines and E.caninus) and Lout fish (A. regius) are infected by two or more different pathogens either by simultaneous or secondary infections

Key words: Groper, Lout, Isolation, Vibrio species, Fresh, Marine water fish