The ninth is hiding behind the rock
But where is the tenth?
When I set up my aquarium again, I bought ten goldfish: fantails, comets, and a shubunkin. I limited myself to ten so as not to have to take my shoes and socks off every time I did a roll call (not that I wear shoes and socks much these days anyway).
I've just done a roll call and there are only NINE ! I counted again and again and left no pebble unturned: one goldfish is definitely missing!
???