[JasonR]

Looks like a glass shrimp to me, I. Had 4 of them last year and they managed to kill many of my fish

 

[JasonR]

Do you keep any fry in the tank? I so I'd remove them ASAP I often caught mine reaching into the breeder grabbing fry, I eventually swapped them for some neons as I was loosing a fish nearly every night. They also used to steal the pellets of my corydoras