I thought I had 10 Tiger Barbs and the other day I counted them and I only had 9. I don't have that much decoration so I would have found it by then If it was hiding or dead. And my aquarium ain't that big either (29g). Not unless one of my other fishes demolished it and ate it, but I highly doubt that. The Tiger Barbs also lives with a Red Tail Shark, 2 Clown Loaches (1 adult, 1 kid), 6 Red Eye Tetra's, and a baby Columbian Shark. And I feed them pretty well I believe (twice a day + give them pellets sometimes for treats). My aquarium ain't fully covered but Tiger barbs ain't jumpers... and I also carefully thoroughly checked the surroundings near the aquarium.. and came up with nothing. So like the topic implies do fishes sometimes dissapear? Or have I miscounted... (I doubt that I miscounted)... anyways there goes my rant.. laters!!