ABSTRACT Invasive species are a major driver of biodiversity loss in protected areas (PAs), yet their impacts in aquatic environments are less well documented. This study investigated the occurrence and distribution of nonnative freshwater fish in federal PAs in Brazil. We analyzed governmental records of nonnative freshwater fish in federal PAs managed by ICMBio up to 2025. A total of 56 nonnative species (38 translocated and 18 introduced) were recorded in 108 PAs, of which 51 were designated as integral protection units and 57 as sustainable use units. Among the introduced species, Oreochromis niloticus and Coptodon rendalli had the highest number of records, and introduced species exhibited a broader spatial distribution than translocated species. Introduced species were also more prevalent in Environmental Protection Areas and National Forests than in Extractive Reserves, suggesting that certain PA categories may be more susceptible to fish introductions. The Amazon basin was the primary source of translocated species, reinforcing its role as a donor region for fish introductions across Brazil. Introduction pathways differed between groups: Introduced species were mainly associated with aquaculture and sport fisheries, whereas translocated species were largely linked to sport fisheries and interbasin connectivity. These findings underscore the urgency of targeted management strategies to curb further introductions and safeguard freshwater biodiversity within PAs. Strengthening PAs' effectiveness will require stricter regulations, improved enforcement and specifically designed strategies to manage nonnative species dispersal.
Orlandi Neto et al. (Sun,) studied this question.