The extreme body sizes of megafishes associated with their high commercial values and recreational interests have made them highly threatened in their native range worldwide by human-induced impacts such as overexploitation. Meanwhile, some megafishes have been introduced outside of their native range. A notable example is the European catfish (Silurus glanis), one of the few siluriforms native to Eastern Europe. It is among the 20 largest freshwater fish worldwide, attaining a total length over 2.7 m and a documented mass of 130 kg. Its distinct phylogeny and extreme size imply many features that are rare among other European fish, including novel behaviours (massive aggregations, beaching), consumption of large bodied prey, fast growth rates, long lifespan, high fecundity, nest guarding and large egg sizes. The spread of the species is likely to continue due to illegal introductions, primarily for recreational angling, coupled with natural range extension associated with climate change. Here, the most recent knowledge on the current distribution and the ecology of the species are reviewed. A series of key research questions are identified that should stimulate new rese arch on this intriguing, yet largely unknown, species and, more generally, on the ecology of freshwater invaders

This work was produced as part of the ‘‘European Catfish Working Group’’ that was financially supported by the University of Toulouse. Individual members of the group were supported by the Spanish Ministry of Economy and Competitiveness (Project CGL2013-43822-R), the Government of Catalonia (ref. 2014 SGR 484), the European Commission (COST Action TD1209), Czech Science Foundation (Project 16-06498S) and the French Laboratory of Excellence Project ‘‘TULIP’’ (ANR-10-LABX-41; ANR-11-IDEX-0002-02)