Simple SummaryInvasive species (IS) can upset both aquatic and terrestrial ecosystems which, in turn, can negatively affect production and economic development. Thus, many countries understand the importance of performing risk assessments on the potential for species to invade an ecosystem. Here, we report on our development of a quantitative risk assessment model to estimate the introduction of invasive aquatic animals into China’s inland waters. This model is based on the analytic hierarchy process (AHP). We propose that the use of this model can provide the basis to better understand the ecological impact of invasive aquatic animals and also effective protocols for risk management should an invasion take place.AbstractThe spread of invasive species (IS) has the potential to upset ecosystem balances. In extreme cases, this can hinder economical utilization of both aquatic (fisheries) and terrestrial (agricultural) systems. As a result, many countries regard risk assessment of IS as an important process for solving the problem of biological invasion. Yet, some IS are purposefully introduced for what is seen as their potential economic benefits. Thus, conducting IS risk assessments and then formulating policies based on scientific information will allow protocols to be developed that can reduce problems associated with IS incursions, whether occurring purposefully or not. However, the risk assessment methods currently adopted by most countries use qualitative or semiquantitative methodologies. Currently, there is a mismatch between qualitative and quantitative assessments. Moreover, most assessment systems are for terrestrial animals. What is needed is an assessment system for aquatic animals; however, those currently available are relatively rudimentary. To fill this gap, we used the analytic hierarchy process (AHP) to build a risk assessment model system for aquatic IS. Our AHP has four primary indexes, twelve secondary indexes, and sixty tertiary indexes. We used this AHP to conduct quantitative risk assessments on five aquatic animals that are typically introduced in China, which have distinct biological characteristics, specific introduction purposes, and can represent different types of aquatic animals. The assessment results show that the risk grade forPterygoplichthys pardalisis high; the risk grade forMacrobrachium rosenbergii,Crassostrea gigas, andTrachemys scriptaelegans is medium; and the grade risk forAmbystoma mexicanumis low. Risk assessment of the introduction of aquatic animals using our AHP is effective, and it provides support for the introduction and healthy breeding of aquatic animals. Thus, the AHP model can provide a basis for decision-making risk management concerning the introduction of species.