I have used two methods that have always worked to catch any fish! Guaranteed.
First:
Remove everything from the tank. This does a few things, once you comitt to it it only takes about 4 hours to do everything you need to do, probably less. Second, it forces you to redo your aquascaping, which can be good. Finally it gives you a chance to feel like you really accomplished something at the end.
Second:
Put a shop vac hose in and let it sit there all night then feed the fish the next day and when the fish you want swim even near to it, TURN IT ON! SUCCKKKKKK there it goes...and if something else to, just fish it out of the container and drop it back it...don't worry they will all survive. Then do what you want with the caught fish.
I am sure the bottle trap works for people, I don't doubt it, but I have never had success. The other thing is the time it takes to capture something that way, you might as well just take everything out.