Biological invasions caused by the introductions of non-native species (NNS) into their non- native ecosystems have long been a global environmental concern. In the Philippines large-scale importation of non-native freshwater fish species for the aquarium and aquaculture industry have been documented as early as 1940s. However, little invasiveness assessment has been done in the past, which resulted to the invasion of some of these exotic species. Thus, in this paper, 25 NNS (Order: Siluriformes) were assessed using the Aquatic Species Invasiveness Screening Kit (AS-ISK) to determine their potential for becoming invasive in the chosen risk assessment (RA) area, as well as their ecological and socioeconomic potential impacts on the Philippines. Based on the comprehensive ROC Curve, with the use of the Youden-J index, overall threshold values of ≥ 35 for basic risk assessment (BRA) and ≥ 47 for BRA + climate change assessment (CCA) were established to categorize the potential invasiveness of each species as low-, medium-, or high-risk. According to BRA, 10 (40%) NNS were screened as highly invasive, 14 (56%) with medium risk, and one (4%) with low risk. For BRA + CCA, 10 (40%) NNS were categorized as highly invasive, 12 (48%) with medium risk, and three (12%) with low risk. These findings highlight the need for more RAs of the non-native fish species that enter the country through the ornamental industry, as well as improved public educational campaigns and comprehensive regulatory and management policies to prevent their future invasion.

In the Philippines, trade in non-native aquatic organisms for ornamental purposes and food consumption has been responsible for their large-scale importation since the 1940s. These non-native organisms, and especially invasive fishes, represent one of the major threats to global biodiversity. However, little is known of the potential threats they pose to native species and ecosystems in the Philippines, where a sound risk analysis strategy is needed to control and manage non-native species. As a case study, nonnative freshwater fish species, both extant and horizon, were screened with the Aquatic Species Invasiveness Screening Kit (AS-ISK) for their risk of being or becoming invasive in Lake Taal – a volcanic crater lake of conservation value. Of the 45 species (13 extant and 32 horizon), 68.9% and 91.1% were ranked as high or very high risk, respectively under current and future climate conditions. This study, which provided evidence that led the Philippines government to adopt the AS-ISK decision-support tool for identifying potentially invasive aquatic species in other water bodies of the country, highlights the need for a comprehensive management strategy to avoid future non-native species introductions and mitigate adverse impacts from extant non-native species.