[Lakea]

I don't know anything about killis or have any experience with jumpy fish. But there could be many factors that lead to them jumping. I think maybe it was just the fresh water coming in, new water just stimulated them and they jumped just out of instinct. Maybe the siphon itself spooked them or people outside of the tank. But next time you will be prepared right? Find some way to cover the tank while you do the water changes. Good luck!