Please help!!! disappearing fish!?

I have a 15 gal tank with minnows, danios, and a goldfish. I have two sucking loaches, what i believe to be chinese algae eaters. They are called hoover and vacuum. Hoover around 3 inches and vacuum around 2. I added vacuum yesterday and he was getting on fine. Ive been out all day and I've just got back !nd coyldnt see him, I've poked around, moved all the decorations and he isnt in there. Where can he be? Please help! Thanks