Predation and ingestion of a barred grass snake Natrix helvetica by a rainbow trout Oncorhynchus mykiss in Lot, France

Barred grass snakes (Natrix helvetica) are found throughout north-west Europe (Kindler & Fritz, 2017) and potentially grow to 1.5 m but rarely attain this size (Speybroeck et al., 2016). They are thought to feed primarily on amphibians and are adept swimmers although rarely seen hunting in open water (Gregory & Isaac, 2004).