The Lixian River, an important tributary of the Red River, originates in Yunnan Province, China, and harbors substantial fish diversity. During the rainy and dry seasons of 2023 and 2024, a systematic fisheries resource investigation of the Lixian River was conducted using traditional fishing methods. From the captured fish specimens, 25 species with comparably large sample size, totaling 652 individuals, were selected for the analysis of length–weight relationships (LWRs) and related biological parameters. The results showed that the ‘b’ values of the LWRs ranged from 1.759 to 3.348, and the condition factor ‘K’ values spanned 1.1095 to 2.7585. Principal component analyses revealed no significant differences in these metrics among fish species occupying distinct inhabiting water layers or taxonomic groups. However, two species exhibited notable variations between main stream and tributary habitats: ‘b’ value of the Onychostoma gerlachi in the main stream was significantly higher than that in the tributaries ( P < 0.05), while Channa gachua displayed the opposite pattern, with significant lower ‘b’ value in the main stream ( P < 0.05). The further canonical correspondence analyses showed that the fish growth in the main stream correlated positively with dissolved oxygen and zooplankton density, but negatively with phytoplankton density, flow velocity, and pH. Conversely, fish in the tributary exhibited inverse correlations with these environmental factors. The findings of this study contribute valuable insights into fish population dynamics, ecosystem health assessment, and the formulation of science-based strategies for sustainable fisheries management in the Lixian River.
Yang et al. (Fri,) studied this question.