Summary This study provides the length–weight relationships (LWRs) for four fish species [Leptobotia rubrilabris (Dabry de Thiersant, 1872); Opsariichthys bidens Günther, 1873; Xenocypris yunnanensis Nichols, 1925; and Sinogastromyzon sichangensis Chang, 1944] collected from the Niulan River, China. Samples were obtained between April 2008 and June 2011 using various types of fishing gear [drift gill nets (mesh: 5 × 5 cm), hook and electro fishing]. A total of 136 specimens belonging to four fish species were analyzed. For each species the sample size, length range, weight range, LWR, 95% confidence intervals of a and b, and coefficient of correlation were determined. Prior to this study, the LWRs for S. sichangensis and X. yunnanensis were unknown. New maximum sizes for S. sichangensis and X. yunnanensis are also provided.

Summary Length–weight relationships were determined for three fish species (Acanthopagrus latus Houttuyn, 1782; Acentrogobius caninus Valenciennes, 1837; and Nematalosa japonica Regan, 1917). Samples were collected from the East China Sea (N 27.306020, E 120.918026), from May to July in 2015–2016. Samples were collected using commercial trawls (5 cm main trawl and 3 cm codend mesh). Length–weight relationships for these three species were determined for the first time.