52 DECEMBER 2024 • WORLD AQUACULTURE • WWW.WAS.ORG Mas pethiya (the Sri Lankan Olive Barb Systomus spilurus), is a freshwater omnivorous fish that is unique to Sri Lanka. It is an excellenttasting food fish with a high market value. Mas pethiya is primarily found in open water systems such as rivers, streams, reservoirs, and irrigation canals of Sri Lanka’s South Western, Mahaweli, dry, and transitional ichthyological zones (Mudalige et al. 2022). The catch of S. spilurus in 2019 was 11260 MT (Mudalige et al. 2022). Previously known scientifically as Puntius sarana (Chakraborty et al. 2007), the name has since been changed to Systomus spilurus (Pethiyagoda et al. 2012). S. spilurus has been classified as a Data Deficient species on Sri Lanka’s 2012 National Red List. The IUCN classified the species as Not Evaluated in 2014. Due to its taste and high nutritional value, S. spilurus has been heavily consumed and its natural populations have declined, mainly due to overexploitation and several ecological changes in its native environment. S. spilurus typically exhibits schooling behavior with some notable characteristics such as good reproductive potential, fast growth rate with an efficient food conversion ratio, a high survival rate, and overall hardiness. Fecundity ranges from 16,000 to 290,000 (Gupta 2015) with good hatching and fertility rates. The average hatching rate is 75.39 percent, while the average fertilization rate is 90.5 percent (Udit et al. 2014). Fertilized eggs are initially translucent but become creamy as the embryo develops (Udit et al. 2014). S. spilurus feed at the surface, but also engage in browsing activities. The feeding habits of S. spilurus are influenced by elements such as time of day, season, fish size, and other factors. Though captive breeding seems a promising method for stock enhancement, larval rearing protocols and stocking densities in particularly have not been evaluated or optimized under Sri Lankan conditions. Creating culture-based fisheries in Sri Lanka is crucial as it will provide a better solution to the issue of limited natural resources. Accordingly, this study aimed to identify the optimal stocking density for S. spilurus postlarvae (PLs) in captivity. As a result, the current study attempted to analyze the growth performance of S. spilurus under different initial stocking densities (0.75 PL/L, 1.25 PL/L, 1.75 PL/L and 2.25 PL/L) in order to determine the most suitable Growth Performance of Endemic Freshwater Fish Systomus spilurus (Sri Lankan Olive Barb) from Postlarvae to Advanced Fry Under Different Stocking Densities Dissanayake D.K.S.D., Athauda A.R.S.B., Walpita C.N. and Mudalige A.R. TOP: Adult Mas pethiya (Systomus spilurus). MIDDLE: FIGURE 1. Prepared tanks prior to stocking. BOTTOM: FIGURE 2. Five-day old fish at stocking.
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