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Summary: Reproductive biology of invasive species is not often studied relative to the invasion process, although it may provide an accurate indicator of the invasion stage. We evaluated the reproductive biology of the exotic fish species Pseudoxiphophorus bimaculatus and Poecilia sphenops in the Teuchitlán River, Jalisco, Mexico by fertility, size at first maturity, sex ratio, gonad maturity stage, gonadosomatic index, condition factor, size‐structure, and habitat. The reproductive variables were related to environmental characteristics using the non‐metric analysis of multidimensional scaling. A total of 1374 specimens of P. bimaculatus and 571 of P. sphenops were captured by seine netting and electrofishing. Maximum fertility of P. bimaculatus was 15.99 ± 2.27 embryonated eggs and embryos and, for P. sphenops, 31.26 ± 4.17. Females predominated among P. bimaculatus, while in P. sphenops the sex ratio was ~1:1. We found mature female and male of P. bimaculatus in degraded sites and juveniles in the springs. Poecilia sphenops reproduced along the river. The establishment of both invasive species in the Teuchitlán River is evidence that they share the reproductive habitat with native fish species, and tend to spread and colonize new areas. [ABSTRACT FROM AUTHOR]

The current distribution and abundance of the 40 species of Goodeidae fishes known from Mexico are described, and a total of 84 Evolutionarily Significant Units (ESUs) is designated within these species. Two species and four ESUs are likely extinct with no captive populations, and three species and eight ESUs are probably extinct in the wild but have at least one captive population in Mexico, the United States, or Europe. Of the 35 extant species, the analyses indicate that nine should be considered as critically endangered, 14 as endangered, nine as vulnerable, and only three as least concern. Twenty-seven of these species have experienced substantial declines in distribution or abundance or both since 2000, and only eight appear to have remained relatively stable. Of the 72 extant ESUs, our analyses indicate that 29 should be considered as critically endangered, 21 as endangered, 18 as vulnerable, and only four as least concern. Brief summaries of the historic and current distributions and abundance of each species are provided, as well as ESU. Three strategies are recommended to conserve Mexican goodeids: protect the best-quality remaining habitats where goodeids still persist, restore degraded habitat and re-introduce species or ESUs where practical, and establish captive populations to ensure continued survival of the many species and ESUs that will almost inevitably go extinct in the coming years. Limited resources require cooperation and collaboration between scientists, conservationists, and aquarium hobbyists for successful captive maintenance., (John Lyons, Kyle R. Piller, Juan Miguel Artigas-Azas, Omar Dominguez-Dominguez, Pablo Gesundheit, Michael Köck, Martina Medina-Nava, Norman Mercado-Silva, Arely Ramírez García, Kearstin M. Findley.)

Efforts to halt freshwater ecosystem degradation in central Mexico can benefit from using bio-monitoring tools that reflect the condition of their biotic integrity. We analyzed the applicability of two fish-based indices of biotic integrity using data from lotic and lentic systems in the Angulo River subbasin (Lerma-Chapala basin). Both independent data from our own collections during two consecutive years, and existing information detailing the ecological attributes of each species, were used to calculate indices of biological integrity for 16 sites in lotic and lentic habitats. We assessed environmental quality by combining independent evaluations water and habitat quality for each site. We found sites with poor, regular and good biotic integrity. Our study did not find sites with good environmental quality. Fish-based IBI scores were strongly and significantly correlated with scores from independent environmental assessment techniques. IBI scores were adequate at representing environmental conditions in most study sites. These results expand the area where a lotic system fish-based IBI can be used, and constitute an initial validation of a lentic system fish-based IBI. Our results suggest that these bio-monitoring tools can be used in future conservation efforts in freshwater ecosystems in the Middle Lerma Basin.