Résumé
The introduction of non-native species in freshwater ecosystems is less the result of natural colonization than their association with lucrative ecosystem services. Although a large part of the world's inland human populations rely on fisheries essentially exploiting wild unmanaged fish populations, many also rely on aquaculture as a sustainable way of providing animal protein daily. Here, the current paradox that opposes economic drivers to conservation perspectives, referred to as the 'Janus syndrome' after the Roman god depicted as having two faces facing opposite directions, is put in perspective with cultural differences, economic parameters and current lack of scientific knowledge. This issue is a crying example of the current Anthropocene with inland aquatic systems being the most severely affected ecosystems in terms of magnitude, frequency and duration of human impacts. There is, unfortunately, no return to a biotic de-homogenization of our freshwater fisheries, but will the lessons learnt be of any use?