Abstract: Phenotype and interior of an endangered species, Semilabeo obscurus, were studied to establish a rapid identification and classification method to facilitate conservation of the germplasm. Traditional morphological and advanced methodologies were applied, and data subjected to statistics and SPSS factor analyses. Linear relationships were found between the body length and the total length, body height, head length, head height, head width, caudal length, orcaudal height, between the head length and the proboscis length, eye diameter, distance between eyes, caudal length, orcaudal height, between the caudal length and the caudal height, between the head height and the head width, as well as between the 21 frame distance and the body length of S. obscurus. Stable linear regression correlations existed between the body length and the head height/head width ratio, caudal length/caudal depth ratio or D_5-7. The principal component feature vector had the greatest absolute value on the loads of D_4-5, D_4-6, D_4-7, D_3-8, D_3-4 and D_5-7, and they correlated. It reflected the characteristic phenotype of the tail section of the fish.Amultidimensional analysis on the phenotype suggested that the ratios of the head height/head width(0.91-0.95), caudal length/caudal height(1.37-1.47) and D_5-7/body length(0.241 3-0.255 3) could be the key indicators for the properties. In general, the composition and structure of the internal organs of S. obscurus were similar to those of Cyprinidae, having long and thin intestines with short and small swim bladders and an intestinal index of 14.15-15.76 (averaging 15.14). The intestines occupied more than 80% of the abdominal cavity of animmature fish; and the length of the bladder, about 14% of the fish body length or 50% of the abdominal cavity length.The information obtained showed the evolution of S. obscurus as it adapted to the environmental changes.