DIVERSITY AND COMMUNITY STRUCTURE OF FRESHWATER FISHES IN URBAN AQUATIC SYSTEMS OF MADIUN CITY, EAST JAVA, INDONESIA

Abstract

Indonesia prioritizes food security, stressing access to healthy and sustainable food sources. Fish play a crucial role as a renewable protein source and contribute to local economic growth. Madiun City, East Java, has rivers, irrigation canals, and ponds that offer potential for local fisheries. However, data on fish biodiversity are limited, despite effective management and conservation efforts. This study examines fish diversity in Madiun waters, identifying native and non-native species. Sampling took place at ten stations, with species identified morphologically. Ecological indices used included Simpson’s Dominance (D), Shannon-Wiener Diversity (H’), Pielou's Evenness (E), Margalef’s Richness (R), and Sorensen’s Similarity (IS). A total of 1,031 individuals from 18 species were recorded, with Cypriniformes being the most common. Station 4 witnessed the rapid growth of the invasive Pterygoplichthys pardalis, which negatively impacted native species. Species richness ranged from 0.98 to 2.64, indicating low diversity. Stations 2 and 9 showed the highest similarity (94%) due to water connectivity. These results indicate initial ecological pressures on Madiun City’s aquatic ecosystem and provide important baseline data for conservation, biodiversity management, and sustainable fisheries, which support increased local food security.