A total of 360 cultured Mugil seheli had clinical signs were collected from private farms in Suez Governorate, Egypt.  M. seheli was subjected to clinical, post -mortem and bacteriological examinations for detection of Yersinia ruckeri. Yersinia ruckeri was identified by biochemical reactions and polymerase chain reaction (PCR). One isolate of Y. ruckeri. The results revealed that the presence of Yersinia ruckeri infection was 68.1%. The highest prevalence of Y. ruckeri infection in cultured M. seheli was during autumn season (80%) followed by spring (72.2%), summer (70%) and then winter (50%). PCR amplification of DNA from Y. ruckeri isolates using 16s rRNA (YER8/10) specific primers for Y. ruckeri resulted in PCR products size of 575 bp. All Y. ruckeri isolates were found to be sensitive to Ciprofloxacin, Tobramycin and Trimethoprim. While resisted Erythromycin, Amoxycillin and Novobiocine.