The year 2015 has been a sad one. It has seen the disappearance of two former directors of the INRA Lake Hydrobiology Unit in Thonon-les-Bains (France): Pierre Laurent and Gérard Balvay. This article summarizes the career of the second scientist, a specialist in limnology, zooplankton diversity and ecology. Gérard Balvay was born on April 29, 1941 in Macon (France), where he received his primary and secondary education, and rapidly became passionate about natural and experimental sciences. He continued his studies with a degree in natural sciences at the Faculty of Sciences of Lyon (1964), a comprehensive study diploma referred to as DEA in France (1965) and a Ph.D. in Biological Sciences (Animal Biology) started in 1965 at the University Lyon I, where he was already attending the Laboratory of Zoology.