comparison the effect of stress on the guppy fish immunized by oral vaccine with chitosan and inactivated immersion vaccine

To create infectious diseases caused by opportunistic pathogens, the pathogen alone is not sufficient to cause the disease. environmental factors and immunodeficiency increase the susceptibility of fish to pathogens, which accelerates by biological stress. stress inducing factors in the prevalence of streptococcus iniae such as high-water temperature especially in summer, high density of fish (male) and low water quality. since disease prevention is a priority, oral and immersion vaccines are used as methods with the least stress and tension.the aim of this experiment is to investigate the immunogenic effect of these vaccines as a solution to reduce stress and disease, which uses guppy fish as an animal model. three groups of 5 guppy fish were selected with 3 replications. in the control groups, oral vaccine containing chitosan and immersion inactivated vaccine were immunized and challenged by injection at the rate of 5 x 105 cfu/fish (10 λ streptococcus iniae). during 30 days using deliberate stress including: increasing the number of males in each group (2), lowering the water temperature by 15°c (twice a month) and stopping oxygen pump aeration (1 hour per day).mortality in the vaccinated groups (26.22% oral and 73.33% immersion) showed a significant difference compared to the control group (93.33%) and births in the control group (5) compared to the oral vaccinated group (3 numbers) showed a significant difference. (p<0.05)this study showed that immunization of stressed guppies, through oral and immersion vaccines, confers protective immunity against streptococcus iniae infection. stressors on fish show that the increase of male fish has played an important role in reducing fertility and causing additional stress to female fish.