Effect of Viral Hemorrhagic Septicemia (VHS) disease on the biometric parameters in rainbow trout (Oncorhynchus mykiss)

To evaluate the influence of VHS disease on rainbow trout biometric traits, this research was conducted. Two hundred eighty-one rainbow trout (88±3.38 g initial weight ) were collected, and after 18 days of adaptation period were randomly divided into five groups. All experimental groups were fed by commercial ration. The first group was selected as a control group (no injection), but the second to fifth groups were injected with 0.03 ml physiological serum, 0.06 ml physiological serum , 0.03 ml VHSV, and 0.06 ml VHSV with the concentration of 4.5x104 pfu.ml - respectively. To diagnose the disease, RT-PCR test was used. The research period was 35 days, and records of body weight, and fish length (standard length, fork length and, total length) were collected on days 28, and 35 of rearing. Mean comparisons of these traits between different groups were conducted using the Tukey test (HSD) and R software. In the results of body weight in the first week after challenge (day 28) significant differences were observed between the control group with VHSV injected groups (p < 0.001) and also between physiological serum with VHSV injected groups (p < 0.05). In the second week after challenge (day 35), there were significant differences (p < 0.001) for body weight between VHSV injected groups with control and physiological injected groups (p < 0.001). In the second week after the challenge for traits related to fish length (standard length, fork length, and total length), there were significant differences between all experimental groups (p < 0.05). Based on the observed results, VHS disease will reduce fish growth, and it will cause economic losses.