Using a 'dither fish'...FYI
Keeping all your fish visible is a bit of a challenge, particularly if you have a tank with a 'pushy' fish in it...maybe a species like a rabbit, which, while itself timid and spooky, is armed with venom, is clad in 'warning' yellow, and when pressed, 'threatens.' Tangs like yellows can get very pushy, even dangerous, too.

First of all, don't overcrowd a tank...you know how you get if you're in a crowded elevator. If the thing were stuck between...