@TG: I though another reason why fish jump is the current. If they recognize a current their instinct tells them to jump. Wasn't that how guppies move up the streams in the wild?
@kyektulu: The dangerous thing is he's not swimming against the current and into the filter, he's jumping into the filter. Therefore, he might die trying.
I would be careful with just letting him do that. He really might miss the filter like rich311k already said, and land on the floor.
Previously: 2x 10gal tank, 45gal aquascaped, 70gal aquascaped
Currently: 16gal FW, 40W CF, ADA Aquasoil Amazonia II/Tahitan Moon Sand, PH 6.5, kH2, gH 4