Cuatro Ciénegas, Coahuila, Mexico, is one of the most unique freshwater ecosystems in North America, comprising more than 200 variably interconnected aquatic bodies that sustain exceptionally high levels of endemism (Fensham et al., 2023). According to Hendrickson et al. (2008), the basin supports sixteen native fish species, eight of which are endemic. Cuatro Ciénegas Shiner, Cyprinella xanthicara, Longfin Gambusia, Gambusia longispinis, Cuatro Ciénegas Platyfish, Xiphophorus gordoni, Cuatro Ciénegas Pupfish, Cyprinodon atrorus, Bifasciate Pupfish, Cyprinodon bifasciatus, Interior Killifish, Lucania interioris, Minckley’s Cichlid, Herichthys minckleyi, and Cuatro Ciénegas Darter, Etheostoma lugoi.

These endemic and other native species face critical threats from invasive alien species (IAS) such as Blue Tilapia, Oreochromis aureus, Jewel Cichlid, Hemichromis guttatus, Common carp, Cyprinus carpio, Louisiana Crayfish, Procambarus clarkii, and the Asian Snail, Melanoides tuberculata. Invasive species have disrupted ecological balance by altering native fish assemblages, increasing interspecific competition, and degrading aquatic habitats, reportedly leading to sharp declines in native fish populations.

While the Comisión Nacional de Áreas Naturales Protegidas has implemented invasive species control programs in Cuatro Ciénegas, their long-term effectiveness has not been formally evaluated. This study aims to address that knowledge gap by (1) assessing current fish assemblages, (2) quantifying the abundance and distribution of native and invasive species, and (3) evaluating the effectiveness of previous control strategies.