Algoflora of fishery ponds in Bukhara province

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 explores the cultivation of Chlorella vulgaris, a species of green microalgae rich in physiologically active compounds, and its application in semi-intensive fish farming systems within the Bukhara region. Over 2022–2023, controlled experiments were carried out at LLC “Buhorobalik” to evaluate the biomass productivity and water-purifying capacity of Chlorella vulgaris under laboratory, semi-industrial, and field conditions. Laboratory trials utilized Muzaffarov’s “04” nutrient medium, along with pond water and horse manure juice as alternative growth substrates. Optimal growth conditions included 26–28 °C, 15–25 thousand lux illumination, constant aeration, and pH of 7.2–7.4, with Chlorella cell counts reaching 48.2 million/mL and wet biomass of 0.5 g/L in 6 days. Field-scale experiments involved cultivating the algae in concrete basins and applying the suspension to fish ponds stocked with herbivorous white fathead (Hypophthalmichthys molitrix). Regular algolization with Chlorella led to a notable improvement in pond water quality: dissolved oxygen increased up to 17.6 mg/L, while ammonium, nitrates, nitrites, chlorides, and sulfates significantly decreased. A measurable suppression of competing blue-green algae was observed, alongside a 20–25% increase in fish productivity. The study demonstrated the feasibility of large-scale Chlorella cultivation using cost-effective nutrient sources like horse manure juice, replacing more expensive synthetic media. The hydrochemical purification of water and biofertilizing potential of Chlorella suspension underscore its significance in integrated aquaculture systems. These findings support the implementation of eco-friendly, sustainable practices in fish farming by integrating microalgae cultivation with aquatic ecosystem management.