Up is down. Down is up. Finkle is Einhorn. Einhorn is Finkle. Your foundation will probably shake to its core when you watch this video of a freshwater fish jumping out of the water to devour a flying bird. For decades, rumors have suggested that there were freshwater fish who could prey on birds in flight. But, this video of an African tigerfish snatching a bird out of the air is the first confirmation of those rumors.

"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 Biology1. 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".

Smit says that he and his group set out to study migration patterns of the African tigerfish in a lake near the border of Botswana and Zimbabwe, they didn't necessarily expect to capture this type of footage.

Nevertheless, during their time at the lake, the researchers saw as many as 20 successful fish strikes on barn swallows (Hirundo rustica) every day. These ranged from pursuits by fish at the surface, followed by leaps, to direct attacks from deeper water. [Nature h/t Reddit]