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João D. Ferraz, Lucas R. Jarduli, Diego A. Z. Garcia, Armando C. R. Casimiro, Fernanda S. de Almeida, & Mário L. Orsi. (2021). Morphological deformities in the invasive driftwood catfish Trachelyopterus galeatus in the Upper Paraná River basin, Brazil: a sign of human impact? J. Fish Biol. https://doi.org/10.1111/jfb.14799

https://onlinelibrary.wiley.com/doi/10.1111/jfb.14799

Abstract
In this study, the authors report morphological deformities in driftwood catfish

Trachelyopterus galeatus

(Auchenipteridae), an invasive catfish occurring in the Upper Paraná River basin, Brazil. The frequency of anomalous individuals reached 18.3% of all catches. X-ray images showed anomalies, or total absence of structures, in the pelvic girdle. The authors also observed the absence of the adipose fin and mental barbels. These findings are of extreme importance for evidencing the anthropogenic impact on aquatic communities as the region suffers within fragmentation by dams and pollution from several human activities. This sort of information can be used in management systems and environmental monitoring, especially to protect other species and the native fish assemblage.

Keywords: basin fragmentation, cascade of reservoirs, contaminants, Paranapanema River, South America

This is a bit odd to me. The fish, T galeatus is not native, and most likely this means a few have been "liberated" in this river. Now, quite a few years later, deformities are found.

I would have expected that a population, based on only a few animals, that is, wityh high inbreeding, will have a good risk of coming in problems due to this inbreeding. Which is, in case of an invasive species, a good thing, it might result in the extirmination of said species.

However, the authors of this article intend to use this information for other purposes, the seam to state that the level of inbreeding in this monitored spicies is alarming for all other species in this area.

These being native species, one would assume their genetic base much broader, and thus far from monitorable by T galeatus.