Messenger RNA (mRNA) vaccines have emerged as a cutting-edge platform for combating infectious diseases. These vaccines consist of a delivery vehicle and one or more nucleic acids encoding single or multiple antigen candidates. Once taken up by host cells, these cells become factories for antigen production. Recently, particularly due to the SARS-CoV-2 pandemic, the production of mRNA vaccines has accelerated, though this progress has not yet been paralleled in cultured fish. Infectious salmon anemia (ISA) is a WOAH-notifiable disease caused by the ISA virus, a single-stranded RNA virus belonging to the Orthomyxoviridae family. Its genome comprises eight single-stranded RNA segments that encode at least ten proteins. Among these, the P3 or fusion [F] protein and the hemagglutinin-esterase [HE] protein have shown promising results in a recent pilot study of ISAv mRNA vaccines. Consequently, the aim of this study was to further explore the effects of these mRNA vaccines on the survival and immune response of Atlantic salmon during a cohabitation experiment. Fish were intramuscularly (i.m.) injected with a 200 µL dose of either a high (1 µg/g), 1:10 (0.1 µg/g), or 1:100 (0.01 µg/g) dilution of the respective vaccine, with PBS serving as a sham control. Half of the fish in each group received a booster after approximately 1000-degree days. In a parallel module, a group of unvaccinated fish was intraperitoneally (i.p.) infected with ISAv (HPR4 isolate at TCID50 1x 10^4). The viral donor fish were kept in a quarantined module for six days post-injection before being introduced to each experimental cohabitation tank, achieving a 5:1 ratio of cohabitant to donor fish. Fish were monitored three times daily, and mortalities were recorded. Serum, head kidney, and spleen samples were collected from all groups (n=5) one day after the onset of mortality. Our findings indicate that, out of the 28 vaccine treatments evaluated, two Fusion protein targets resulted in significantly higher survival rates compared to sham vaccinates, consistent with the pilot study. Current analyses are focused on assessing the presence of specific ISAv-antibodies using ELISA. Moreover, the modulation of genes related to vaccination and antiviral responses in Atlantic salmon has been assesed by RT-qPCR.