Abstract
Mycobacteriosis is a bacterial disease caused by Mycobacterium spp. that is common in captive, wild and research fish species. The overall goal of this thesis was to investigate mycobacteriosis in laboratory zebrafish in order to increase our understanding of this disease with the intention of influencing control and management practices. First, disease prevention through embryo disinfection was investigated. The effectiveness of several disinfectants were evaluated and povidone-iodine was identified as an effective disinfectant in vitro, it was then evaluated in vivo and showed minimal effects embryo health. Second, the potential of antibiotic treatment against mycobacteriosis in zebrafish was evaluated in vitro where tigecycline and clarithromycin were identified as key drug candidates. The tolerance and efficacy of both antibiotics were tested in vivo in adult zebrafish; where treatments were well tolerated and resulted in a decreased severity in establish mycobacterial infections. Last, natural modes of transmission were examined. Transmission between tank biofilms and zebrafish was demonstrated and the role mycobacterial biofilms play as both a reservoir for and source of Mycobacterium spp. in zebrafish tanks was identified. Finally, the role that live feeds play as a vector of mycobacterial transmission to zebrafish was tested and common zebrafish feeds are able to transmit Mycobacterium spp. to zebrafish. Altogether, these studies contribute to our current knowledge of mycobacterial infections in laboratory zebrafish and inform management. These results are also of use to other fish species as well.