Predicting aquatic invasions in a megadiverse region: Maximum‐entropy‐based modelling of six alien fish species in Malaysia

1. There has been a recent increase in the occurrence and proliferation of alien fish species in rivers, lakes, and reservoirs of Malaysia, posing a significant risk to native biodiversity. This increase has been largely caused by the unmanaged aquaculture and aquarium pet trade.
2. At present, very little information is available on the diversity and distribution of alien fish species in freshwater ecosystems of Malaysia, as well as their current and future threats.
3. Using the MaxEnt model, the potential habitat suitability and future invasion ranges of six alien fish species (Cichla ocellaris, Clarias gariepinus, Oreochromis mossambicus, Oreochromis niloticus, Poecilia reticulata, and Pterygoplichthys pardalis) in Peninsular and East Malaysia (Borneo) were determined.
4. All six alien fish species investigated, have high potential to invade eight states in Peninsular Malaysia (Johor, Kelantan, Malacca, Negeri Sembilan, Pahang, Perak, Selangor, and Terengganu), and much of East Malaysia. The results also indicate that alien fish are likely to invade the majority of the 444 protected areas in the country, particularly those located in Sabah and Sarawak, which are known for their high fish diversity and endemism.
5. Minimum temperature of the coldest month (Bio 6) and isothermality (Bio 3) significantly influence potential invasion habitats for all six alien fish species in Malaysia. The country's hot and humid climate makes it ideal for the survival and proliferation of alien species except for P. pardalis.
6. These findings will help conservation planners and managers in identifying areas of high concern for alien freshwater fish species in Malaysia, and to pre-emptively mitigate and manage their future invasion.