When I fed my fish today, I noticed litle guys peeking out from the rocks. My fish are parents!
There are at least two of them, and they are small enough to be eaten in one bite by the other fish. Here's to hoping they survive. Though I doubt it. But to help them, I will refrain from cleaning the tank (sucking them up and depriving them of a place in the rocks to hide) for a few weeks and see what happens.