The following story was sent to me by email and the person wished to remain anonymous for security reasons.
I’ve been an aquarist for quite some time now and throughout my years I’ve never had a fish quite like the kuhli loach. When I first got into the hobby, I had a community tank with some head-and-tail-light tetras, some cory cats, about a dozen guppies, about ten rasboras, and three kuhli loaches. The kuhli loaches hid during most of the day, only to come out at night and eat. After a few months of having my tank, my kuhlis mysteriously disappeared. At the time I just assumed that the other fish ate them or that they accidentally got carried out in a water change (Wizzkid’s note: How would they get carried out in a water change?). After I had my tank for a year, I fell in love with Oscars. Not having the money to buy another tank, I traded my fish in for a pair of Oscars and put them in my old tank. After about two years, I don’t know why, but I decided to do a complete cleaning of my tank. When I lifted the undergravel filter plate, low and behold, there were my kuhlis, alive and well. It appeared that they had squirmed down through the plates and had been living off of uneaten and bacteria brought down from the power heads!