Abstract: On the basis of redescription of Trichodina centrostrigata Basson, Van As & Papema, 1983, we further explored the population diversity and host preference based on morphological characteristics, molecular characteristics and phylogenic analyses. The results showed that the three populations, viz. Trichodina centrostrigata (KP295473), Trichodina centrostrigata (W) and Trichodina centrostrigata (Q), had no obvious population differentiation in the last four years. Next, T. centrostrigata clustered trichodinids that live in the marine environment, which indicates a closer relationship between them. Again, T. centrostrigata has a strong parasitic specificity because they mainly parasitize the euryhaline tilapia, and only very few can parasitize other freshwater fishes. Finally, the host tilapia infection rate for T. centrostrigata in this study is 100%, which suggested that T. centrostrigata may be a potential pathogeny in the tilapia aquaculture industry.