Abstract: Transparent zebrafish embryos have been an attractive model for infection studies related to human pathogens, however they do not survive core human body temperatures and therefore the physiological relevant behaviour of pathogens in a host environment might not be fully recapitulated. To overcome this issue, we have selected the thermotolerant Arabian killifish as a novel model for infection experiments as they can survive at human body temperatures, both normal and fever conditions. In the seminar, our studies of the virulence of Candida albicans in Arabian killifish will be outlined. C. albicans is a commensal but opportunistic fungal pathogen in humans and can cause lethal candidiasis in immunocompromised patients. By testing different genetic lines of C. albicans, we have found that virulence of each strain can be significantly different at the human body temperature 37’C compared with the 30’C. To improve the optical clarity of the embryos, mutant strains which do not generate melanin and fluorescent pigments were generated by CRISPR/Cas9 KO. We have also generated several fluorescent transgenic fish lines for visualising tissues including immune cell lineages. In the seminar, use of the data from the Arabian killifish model, temperature dependent virulence of the C. albicans and potential application of the model for other pathogens and drug testing will be discussed.