Water Quality in Koi Fish (Cyprinus carpio) Concrete Ponds with Filtration in Nglegok District, Blitar Regency

Water is the most precious natural resource and its quality must be checked before use. Water sources should be monitored regularly to determine whether they are in good condition or not. The poor water quality is not only an indicator of environmental degradation but also a threat to ecosystems, including aquaculture activities. The success of koi fish farming is generally determined by an understanding of the physical, chemical, and biological qualities of water. It is necessary to research water quality analysis to determine the environmental condition through a comparison of two different types of ponds (traditional and filter). The research method is descriptive. Water quality analysis in each pond includes parameters of temperature, pH, water brightness (cm), Dissolved Oxygen (DO), Total Organic Matter (TOM), Carbon dioxide (CO₂), Orthophosphate, Ammonia, Nitrate, Biological Oxygen Demand (BOD), Total Suspended Solid (TSS) and Chemical Oxygen Demand (COD). This research activity was carried out as a community service, related to monitoring the water quality of koi fish farming ponds in the Nglegok sub-district, Blitar Regency, East Java. The results of temperature in traditional ponds were lower than in filter ponds. Meanwhile, CO₂ and ammonia levels in traditional ponds and filter ponds exceed the optimal quality standard for the koi fish viability. However, other parameters are quite good for koi fish cultivation. In cultivation activities, three important components are interconnected and affect each other, the environment, the host, and the pathogen. Optimization of water quality management can be applied by using aeration or filtration, calculating feed conversion to reduce organic material residues, and regularly changing the water.