Hi! I don't know whether this is still relevant or not, I've just found another way to catch them. I've discovered it from compiled information around the other forum, so I decided to significantly decrease the water volume (since I'm also re-scape and clean my aquarium, so I decrease it by 90%) AFTER taking our all your aquarium pet.
Then add cold water almost 40% the about of the remaining volume, apparently, the temperature shock lures them out.
Then you just pick it one by one, after that, readjust your aquarium temperature then reacclimate your pet again to avoid temperature shock.
Works like a charm!
By the way, thank you for all the input in this forum as well.