The importation of non-native fish species into Malaysia began as early as the 19th century, when a substantial number of non-native fishes were introduced from southern China, heralding the beginning of aquaculture in Malaysia. In this review, we analyzed the available literature on the history, checklists, current status, production trends, and potential ecological and socioeconomic impacts of non-native
\nfreshwater fishes in Malaysia. We identified a total of 30 non-native food fishes belonging to 12 families, with Cichlidae occurring the most frequently. Moreover, 173 species from 40 families of non-native freshwater ornamental, recreational and biological control fishes were also listed. The aquaculture production and wholesale
\nvalue were significantly higher (p < 0.05) for non-native species, as compared to native species. Approximately 93% (1,317,990 metric tonnes (MT)) of aquaculture production and 85.6% (RM 7.4 billion) of wholesale value are from non-native species. However, for inland freshwater captured fisheries, the landing and wholesale
\nvalues were significantly higher (p < 0.05) for native species than the non-native species. Non-native species only occupied approximately 28.6% (18,227 MT) of the landing, and 14.2% (RM 110 million) of wholesale value, respectively. For the ornamental fish production, the highest value was recorded in the year 2012 (RM 629 million), but dipped to its lowest value in 2017 (RM 327 million). The cyprinids that are mostly represented by non-native species recorded the highest
\nvalue (RM 112 million) in the year 2018, followed by osteoglossids that are mainly represented by the native Asian arowana (RM 108 million). Despite the massive economic contribution from these non-native fishes, some of these fish present important ecological and socioeconomic threats to Malaysia. Several recommendations
\nare proposed for a win-win situation between the economic gains and environmental threats caused by these non-native fishes.

One of the most dominant concepts in invasion ecology is the stage-based invasion model, consisting of transport, introduction, establishment and spread. Many species fail at one of the stages, with propagule pressure (i.e. number of introduced individuals) identified as a principal factor affecting establishment success. Population characteristics such as phenotypic plasticity and beneficial life history traits may facilitate successful transition of species through different stages of the process; however, studies on the latter are not so common and most of those studies focus on terrestrial taxa. In this study, we hypothesized seven life history traits that may be beneficial for invasion success of aquatic species, and determined those traits for established non-indigenous species (NIS) in the North and Baltic Seas (i.e. marine environment) and Great Lakes-St. Lawrence River regions (i.e. freshwater environment). This is the first study that examined certain life history traits of all NIS established in particular regions, as well as compared those traits between marine and freshwater habitats. Our study determined some differences in life history traits between NIS in the marine and freshwater habitats. Those differences were connected to different taxonomic groups that were dominant NIS in these two types of habitats. Furthermore, species originating from different donor regions had also different life history traits. The majority of NIS in both regions were r-strategists. There was a significantly higher number of NIS that were able to reproduce both asexually and sexually and to produce dormant stages in the freshwater than in marine habitat. Finally, as r-strategy, asexual reproduction and dormancy were dominant traits of NIS in the freshwater habitat, freshwater ecosystems may be under greater invasion risk than marine ones, as those traits reduce both demographic and environmental stochasticity during the invasion process.

Although competition and predation are mechanisms more studied in biological invasions, ecologists and conservation managers have become aware of the threat imposed by the co-introduction of parasites.Parasites can be co-introduced into new areas with a non-native host, and become co-invaders when they spill over to native hosts.The copepod Lernaea cyprinacea was presumably co-introduced to Patagonia along with the common carp, Cyprinus carpio.Our aims were to compose an updated list of the hosts of L. cyprinacea and its distribution in South America, to confirm the specific identity of Patagonian specimens using molecular tools, and to enlarge the list of hosts and localities in Patagonia, by comparing infection rates between non-native and native fishes to evaluate spillover processes.Between the years 2011 and 2017, native and non-native fish species were collected in freshwater environments from Northern Patagonia in basins where common carp and non-native fishes belonging to the Brazilian biogeographic sub-region, like Characiforms, Siluriforms, and Cyprinodontiforms, have been introduced.The sampled fishes were examined under a stereoscopic microscope to search for L. cyprinacea.At present, in South America, records of L. cyprinacea parasitizing native and non-native hosts exist for Colombia, Uruguay, Brazil, Chile and Argentina, with a total of 43 host fish species.Complete sequence data from the 18S region corroborate the identity of the Patagonian parasite based on morphological characteristics.A total of 754 fish belonging to 13 species were collected and 388 copepods were recovered.Lernaea cyprinacea was registered in almost every surveyed freshwater system in Patagonia, even in places where the original host, C. carpio, was absent.The copepod was found parasitizing two native and four non-native fish species, and in general, native fishes showed higher infection values.The present study enlarges the list of localities in Patagonia.It also provides molecular confirmation of the specific identity.In summary, our results show how an alien parasite may switch host and disperse beyond the actual distribution range of the original host.This study provides an overview of the process of colonization of L. cyprinacea in Patagonia, which represents a threat to native species due to its pathogenicity.