Diversity and Habitat Adaptation of Endemic Fish in Tropical River Ecosystems

This study examines the diversity and habitat adaptation of endemic fish in Lake Tondano and the Tondano River, with comparisons to urban rivers in Manado, North Sulawesi. Using a descriptive-quantitative approach at nine survey sites, biotic data were collected using various fishing methods and abiotic data were measured through key environmental parameters. Analysis using the Shannon-Wiener Index, correlation tests, and multivariate methods revealed that the upstream segment of the Tondano River had the highest diversity (H' = 2.71), while urban rivers showed low diversity due to habitat degradation. Environmental factors such as current, dissolved oxygen, and substrate significantly influenced species distribution and demonstrated clear morphological and behavioral adaptations. The study concludes that endemic fish diversity and adaptation are strongly shaped by ecological conditions, providing valuable insights for tropical aquatic biology and supporting conservation and sustainable management of endemic fish resources.