I have 8 white skirt tetras, 8 albino cory cats, and had 8 danios. Now I have 7 danios. One mysteriously disappeared. I am very doubtful it is hiding because my danios don't do that; all they do is swim at the surface.
It is impossible for the fish to have eaten the danio. They are too small.
It is impossible for the fish to have jumped out. The tank is fully covered. I checked around the tank, searching for a good 30 minutes - nothing found.
My fish isn't dead. The cory cats would have easily started feasting on it. They eat anything that's at the bottom, essentially. (Perhaps it died while I wasn't around?)
My filter doesn't contain the fish.
No sign of a fish skeleton ANYWHERE.
What could have happened to it?