Lakes Reserv Res Manage. 2019;24:255–258. wileyonlinelibrary.com/journal/lre | 255 © 2019 John Wiley & Sons Australia, Ltd 1 | INTRODUCTION The Silver Cyprinid (Pellegrin, 1904) is a small zooplanktivorous fish endemic to Lake Victoria. The Rastrineobola argentea fish‐ ery in the past was considered to be insignificant, only being ex‐ ploited at the rural level to contribute to the diet and livelihoods of marginalized communities. This assumption no longer holds today; however, since this is now one of the most important Lake Victoria fisheries (Obiero et al., 2015; Ogello, Obiero, & Munguti, 2013). The Nile perch fishery is mainly for export, and the catch of Nile tilapia has significantly decreased. The R. argentea fishery provided employment to many women living along the lake re‐ gion, unlike the male‐dominated Nile perch fishery. R. argentea is a major source of protein for the fishing communities, and also a major constituent in the manufacture of commercial animal feeds. The critical habitats for R. argentea include the shoreline, sheltered bays and river mouths, which are also known to be their breeding and nursery grounds. Its diet consists primarily of zooplankton and insects (Getabu, Tumwebaze, & MacLennan, 2003; Yongo, Manyala, Kito, et al., 2016; Yongo, Manyala, Njiru, et al., 2016). Observations of the size at massive maturity of R. argentea in Lake Victoria vary, depending on the region of the lake being consid‐ ered (Bayona et al. 2001; Manyala, Nyawade, & Rabuor, 1992; Okedi, 1973; Wandera, 1993; Wanink, 1998; Yongo, Manyala, Njiru, et al., 2016). Compared with other species, R. argentea has the highest fecundity, although its absolute fecundity has halved Received: 22 October 2018 | Revised: 8 July 2019 | Accepted: 24 July 2019 DOI: 10.1111/lre.12281 ORIGINAL ARTICLE Changes in some biological parameters of the silver cyprinid, Rastrineobola argentea (Pellegrin, 1904) in the Nyanza Gulf of Lake Victoria, Kenya Edwine Yongo | Joshua Olukoye | Ali Makame | Brian Chebon Department of Fisheries and Aquatic Sciences, University of Eldoret, Eldoret, Kenya Correspondence Edwine Yongo, Department of Fisheries and Aquatic Sciences, University of Eldoret, P.O. Box 1125‐30100, Eldoret, Kenya. Email: edwineyongo@gmail.com Abstract The study examined length–weight relationship, condition factor, size at 50% ma‐ turity and fecundity of Rastrineobola argentea in the Nyanza Gulf of Lake Victoria, Kenya. The 500 fish examined had a mean length of 39.4 ± 0.3 mm SL, ranging from 17 to 55 mm SL and weighed between 0.08 and 2.44 g. The length–frequency analy‐ sis indicated a unimodal distribution between 35 and 40 mm SL, with a modal length at 37 mm SL. The fish exhibited a positive allometric growth pattern (b = 3.4). The condition factor for all fish was 1.02. Male fish showed a decreasing trend in condi‐ tion factor with increasing body length, while females exhibited an increasing trend. The length at 50% maturity was estimated at 43 and 44 mm SL for males and females, respectively. The smallest mature male was 41 mm SL and 42 mm SL for females, with 100% maturity already exhibited at 49 mm SL. Fecundity varied from 235 eggs for 33 mm SL to 2,309 eggs for 54 mm SL fish. positive linear relationships were found between fecundity against standard length and ovary weight. Comparisons with pre‐ vious studies in this lake over time indicated a decrease in length at maturity and an increase in fecundity, which are strategies to maximize reproductive success. The findings of this study provide useful information for managing the fishery. KEYWORDS condition, fecundity, maturity, silver cyprinid