I was looking for a top-layer-dwelling-fish for my community tank and I've been keeping a couple of Striped Panchax Killifish, aka Aplocheilis Linneatus for that purpose.
Their behaviour is like a pike and the fish indeed stays at the top of the tank for 95% of the time. They become around 3,5" and can get 4 years of age.
Sometimes the 2 of them roam the rest of the tank together.
They'll eat anything that hits the water and will bite the bloodworms from my fingers.
Nowadays they got the habit of stealing the algaewafers meant for my plecos, as you can see in the video.
Bit crappy vid, because of the lighting, the tank is very dimly lit.
But you get a good look at 1 min into the video.


Very cool fish, but you got to seal your tank off completely, and take care during WC, cause these guys can jump.
If you got a communitytank with not too small fish (they can be predatory to smaller fish), the Panchax can be a great addition to the tank and is very much worth looking into!