Ptychobarbus dipogon is one of the most important endemic fish species in the upper and middle reaches of the Yarlung Tsangpo River. However, P. dipogon populations have declined sharply in recent years and their biology is poorly understood. To better understand the biology of P. dipogon and their relationship with management, we describe the relationships between standard length and body weight and age, verify annual growth of lapilli otolith annuli, and estimate P. dipogon growth. The age structure and growth characteristics of P. dipogon were investigated by examining 956 specimens collected in the Yarlung Tsangpo River during 2008-2009 and 2012-2013. Standard lengths were 146-569 mm in females, 167-506 mm in males, and 78-297 mm in some undetermined specimens. Otolith annuli formed from March-June each year. Estimated ages were 3-24 years in females, 3-13 years in males, and 2-6 years in undetermined specimens, respectively. The standard length-body weight relationships were described by W= 2.494 * 10~(-5)L_s~(2.877) for females and W= 2.790*10~(-5)L_s~(2.856) for males. The von Bertalanffy growth equations were: L_t= 606.9[1- e~(-0.114(t+0.163))] and Wt=2538.4[1-e~(-0.114(t+0.163))]~(2.88) for females and L_t=496.3[1-e~(-0.162(t-0.018))] and W_t=1391.1[1- e~(-0.162(t-0.018))]~(2.86) for males. The growth inflexion points were 9.1 years for females and 6.5 years for males, and the corresponding standard lengths and body weights were 396.0 mm and 743.6 g for females and 322.5 mm and 406.3 g for males, respectively. Our results show that the P. dipogon population tended to be younger. Climate changes, biological invasion, and over-exploitation could be the main factors threatening P. dipogon stocks. The sound management policies proposed in this study should be implemented to conserve P. dipogon populations.