fish-inBOLIVIA: An integrative and updated checklist of the introduced and native ichthyofauna.

This study presents the most comprehensive and updated checklist of fish species in Bolivia, integrating nearly two centuries of systematic literature (1855-2025) with physical records from the UMSS-Museo de Historia Natural Alcide d'Orbigny Fish Collection. The study identifies a total richness of 1,095 taxa, comprising 1,079 native and 16 introduced species, marking a significant advancement in the documentation of South American ichthyofauna. Taxonomically, the fauna spans 17 orders, 57 families, and 379 genera. The diversity is dominated by the orders Characiformes (431 spp.) and Siluriformes (407 spp.), with Loricariidae and Acestrorhamphidae emerging as the most species-rich families. Hydrographically, the Amazon basin exhibits the highest diversity with 943 species (including 15 introduced), followed by the De La Plata basin with 363 species (five introduced) and the endorheic Altiplano basin with 31 species (two introduced). A significant finding is the high degree of native faunal exclusivity in the Amazon, which contains 690 species recorded only in that basin; a number notably higher than the 120 recorded only for De La Plata. Conversely, the Altiplano, while lower in total richness, is characterized by an important number of restricted-range species corresponding to the genera Orestias and Trichomycterus. Hierarchical Cluster Analysis (HCA) validates these findings, confirming three well-defined primary clusters that mirror Bolivia's major hydrological systems and their historical biogeographic isolation. The study also tracks 16 established non-native species introduced for aquaculture, fisheries, and the aquarium trade. Conservation assessments highlight that 43 species are currently listed in the Bolivian Red Book and 52 in the IUCN Red List. This synthesis addresses critical knowledge gaps and provides a vital baseline for ecological research, biogeographic modeling, and the sustainable management of Bolivia's megadiverse but increasingly threatened aquatic ecosystems.