We have a very sneaky clown loach in our aquarium. She manages to completely disappear for hours at a time! We don't have that many hiding spaces, so I have no idea where she is. After several days of not being able to find her, I thought perhaps she'd died and been eaten by the other occupants of the tank, but yesterday when I got home from work, she was out and begging for food along with the other two:
pleco, who would disappear for months at a time. Ultimately, I was able to discover her hiding place. Unfortunately, she died in August while we were on vacation. It was a shock as we should have had her for many years yet. We have not replaced her, opting for more frequent tank cleanings.