one of my clown loaches have funny strange blackish spots around his mouth and some around on his back. they are not growths they just look like someone has got a pen a put dots on him with a felt tip pen. ill try and get a picture soon.
if you turn off the lights for about 15 mins they will think its time to sleep, so if you then turn the lights back on after 15 mins, they should be still sleeping and very still. They normally lose some color while sleeping, but if you take the pics as soon as you turn the light on they will be quite still