The cameras recorded guppies actually preparing themselves for jumps by first backing up (as if winding up) prior to launch. This behavior indicates the act of hurling itself out of the water is deliberate.
Fish jump from water for all sorts of reasons. Some do it for food. Some do it to escape predators. Some dart vertically as a courtship ritual (and in our shallow tanks, this usually means darting out of the water). UoM researchers hypothesize that guppies jump in an attempt find new waters and new places to live.
The research, “Aerial jumping in the Trinidadian guppy (Poecilia reticulata),” is published in the scientific journal PlosONE.