BACKGROUND: Strepotococcosis caused by Streptococcus iniae is one of the important emerging bacterial diseases in aquaculture sector worldwide. ObjectiveS: In this study, the genetic diversity of S. iniae strains was assessed in some rainbow trout farms in Iran. Methods: Gram positive and catalase negative bacterial isolates were first obtained from 100 trout fish farms in 8 states using routine bacteriological and molecular (PCR) works. The genetic diversity of these bacterial isolates was then assessed using restriction fragment length polymorphism (RFLP) method. Results: Seventy-seven strains of Gram positive and catalase negative cocci were isolated from diseased trout. PCR analysis resulted in identification of 27 strains as S. iniae. RFLP analysis of these strains using 9 digestive enzymes resulted in production of 29 bands with different molecular weight (62-940bp).  Phylogenetic relationship of these strains grouped them in two distinct clusters. Twenty-six strains from Tehran, Mazandaran, Gilan, Lorstan, Fars and Charmaha-va-Bakhtiary provinces showed high homogeneous similarity above 99%, while one strain from Mazandaran province showed some differences with other strains. ConclusionS: S. iniae isolates in trout aquaculture in Iran possess  low genetic diversity.

BACKGROUND: Increase in aquatic production is dependent on raw materials, quality of diet, feed manufacture technology and optimum feed formulation. OBJECTIVES: The aim of this study was investigation and quality control feed of FFT, GFT1 and GFT2 of rainbow trout in farm and fish feed factory producers in Chaharmahal and Bakhtiari province. METHODS: In this study samples of FFT, GFT1 and GFT2 of diets were randomly taken from farm and fish feed factory producers in Chaharmahal and Bakhtiari province. Samples were analyzed for moisture, crud protein (CP), ether extract (EE), ash, phosphorous, TVN, Total count and coliform count. RESULTS: The results showed, diet CP was differs significantly (p<0.05) from many of the feeds. In addition nutrients of CP, phosphorous and EE of diets were differed slightly from rainbow trout requirement and in some cases were lower than instance requirement. The index of TVN that shows free nitrogen, was higher than standard in all samples. Total count and coliform count were different  between some of the other feed factories. CONCLUSIONS: Better management in fish feed factories  must be applied to balance the nutrient requirements  of the rainbow trout diet in different stages of growth, by using fresh, suitable and special feed materials.

BACKGROUND: Yersinia ruckeri is the etiological agent of enteric red mouth (ERM) or yersinioisis disease, one of the important bacterial diseases in the cultured salmonids. OBJECTIVES: The purpose of present study was detection of gyrA gene (quinolone resistance) in the Y. ruckeri bacterium. METHODS: In this study fish were evaluated in average size 8-12 cm from six rainbow trout farms in Chahar Mahal va Bakhtiyari province (Iran). In each farm 10 fish (totally 60) suspected to yersinioisis were randomly selected; sampling was done from lower part of intestine and cultured on Trpticase Soy Agar (TSA). The mediums were transferred to incubator and kept at 22 °C for 48 hours. Pure colonies which are grown on the mediums were tested by catalase, oxidase and gram staining, then those of gram-negative, catalase positive and  oxidase negative were diagnosed, and cultured on Waltman- Shots medium (as specific medium for Y. ruckeri). These mediums were incubated at 22 °C for 48 h. Colonies that were grown were tested by PCR method for Y.ruckeri detection. Then, in the identified strains of Y.ruckeri gyrA gene were detected by PCR test. RESULTS: The results of bacteriological, biochemical and molecular tests showed that three cases out of total isolates were identified as Y. ruckeri. In all isolates of Y. ruckeri, gyrA gene was identified by molecular test. CONCLUSIONS: Identification of quinolone resistance gene in Y. ruckeri isolates can be the reason of low efficacy of these classes of antibiotics in the aquaculture. ِTherefore, the policy of treatment should be changed specially in enteric red mouth disease.