South Africa, as a signatory of the Convention on Biological Diversity, has an obligation to identify, prioritise and manage alien species and their introduction pathways. However, this requires knowledge of the introduction pathways, factors influencing establishment success, invasive potential, current distributions and ecological impacts. In this paper, the trait-based Fish Invasiveness Scoring Kit (FISK) was assessed to determine its utility to predict the invasion risk posed by fish species proposed for introduction into South Africa. The calibration of FISK for South Africa was conducted retrospectively on species that have historically been introduced into the wild and for which the current invasion status is known. The overall FISK score, its two main categories (biogeography and biology) and the eight sub-categories, were evaluated for use as single parameter surrogates for the full assessment. Only the “Biogeography and History”, “Climate and Distribution” and “Invasive Elsewhere” sub-categories were significantly different between invasive (n=16) and non-invasive (n=11) species. We found that a FISK score of 14 delineated between species that could become invasive in South Africa and those that are unlikely to become invasive. The Calibrated FISK was then used to evaluate whether three species recently proposed for importation for aquaculture could be invasive in South Africa. We found that of the three species, Siluris glanis had a high risk of becoming invasive in South Africa, Lates calcarifer had an upper medium risk of becoming invasive and was thus likely to be invasive and Oncorhynchus tshawytscha has a lower medium risk of becoming invasive and was unlikely to be invasive in South Africa. The use of FISK demonstrated its potential as a useful risk assessment tool to evaluate the invasion risk posed by species proposed for use in aquaculture. For the large number of pet-trade imports, we recommend a rapid screening assessment to flag potentially high-risk species followed by a full FISK assessment of flagged species.