“The whole action of jumping and catching the swallow in flight happens so incredibly quickly that after we first saw it, it took all of us a while to really fully comprehend what we had just seen,” says Nico Smit, director of the Unit for Environmental Sciences and Management at North-West University in Potchefstroom, South Africa.

After the images did sink in, he adds, “the first reaction was one of pure joy, because we realized that we were spectators to something really incredible and unique”.

This is the first confirmed record of a freshwater fish preying on birds in flight, the team reports in the Journal of Fish Biology. Rumours of such behaviour by the African tigerfish (Hydrocynus vittatus), which has been reported as reaching one metre in length, have circulated since the 1940s. But Smit says that his team was “never really convinced by the anecdotal reports”. So, when they set out to study of the migration and habitat use of these animals in a South African lake in the Mapungubwe National Park, near the border with Botswana and Zimbabwe, they were not necessarily looking for fish flying out of the water.