Reproduction of chlorella (chlorella vulgaris) under laboratory conditions and its application in fish farming

¹ Bukhara State University, Bukhara, Uzbekistan
² Bukhara State Medical Institute named after Abu Ali ibn Sino, Bukhara, Uzbekistan
³ Urgench State University named after Abu Rayhan Beruni, Urgench, Uzbekistan

^* Corresponding author: otabek90u@gmail.com

Abstract

This study investigates the reproduction dynamics of Chlorella vulgaris under controlled laboratory conditions and evaluates its application in enhancing aquaculture productivity. Pure cultures of Ch. vulgaris were propagated in photobioreactor systems under optimized conditions involving varied light intensities, pH ranges, and nutrient concentrations. Reproductive performance was assessed through growth rate, chlorophyll content, cell density, and autosporulation analysis. Maximum biomass yield was obtained at 25°C, pH 7.5, and light intensity of 150 µmol photons m⁻² s⁻¹ using nitrogen-enriched media. Harvested biomass was incorporated into experimental aquafeeds at 5% and 10% inclusion levels, and its effect on the growth performance, feed efficiency, and water quality in Oreochromis niloticus (Nile tilapia) was assessed over a 45-day period in recirculating aquaculture systems. Results demonstrated that Ch. vulgaris supplementation significantly improved specific growth rate (SGR), feed conversion ratio (FCR), and fish survival compared to control groups. Furthermore, live microalgae addition contributed to reduced ammonia and nitrate levels, confirming its biofiltration capacity. This study highlights the dual role of Chlorella vulgaris as a nutrient-rich feed additive and an eco-functional agent in aquaculture. The findings support the integration of laboratory-optimized Ch. vulgaris into sustainable fish farming systems and provide a scalable model for enhancing productivity while improving environmental resilience.