When I started my tank I purchased 10 zebra danios to help with the cycling. A couple were lost in the initial cycling, but most survived.
A couple of weeks ago I noticed one of the remaining danios was missing all of the sudden unexpectedly. I had suctioned the tank a couple of hours earlier and although I don't think I sucked up a fish I chalked it up to a possibility.
But yesterday I was missing a couple more and now have figured out where they are going.
My Oscar is snacking on them.