Objective To study the characteristics of transparent tiger barb Puntius tetrazona infected with Mycobacterium marinum and develop an infection model.Method P. tetrazona were infected with M. marinum via intraperitoneal injection, intramuscular injection and cohabitation experiment. The fish characteristics after infection were observed. Distribution of bacteria and pathological changes in the fish were evaluated by wet-mount preparations and tissue slices.Result Both injection methods resulted in pathologic damages around the infection sites, and gradually led to fish death. The disease progression was slow for the fish in the cohabitation experiment, and the fish appeared thin and pale. The pathogenic bacteria were isolated from fish with different infection treatments. Granulomas, the classic symptom for infection, were observed in major organs. M. marinum could be specifically stained by Ziehl-Neelsen stain. A number of melano-macrophage centers developed in different organs, and the organs were associated with different degrees of pathologic lesion.Conclusion The transparent line of tiger barb is a susceptible host of M. marinum, and the symptoms can be conveniently observed with typical pathological changes. P. tetrazona is an excellent model for further infection research.