I don't think it's either of those two. Corydoras bilineatus appears to have a gold sheen to him, mine definately doesn't and all the pictures I found of Sterba's Cory Cat seem to have patterns on the tail fin, my cory doesn't.
Maybe he's a hybrid of the two?
Is it a corydoras nanus do you think?
Iv'e found it!! He must be a male corydoras napoensis!!!!
thanks for the help anyways!
It is a Corydoras bilineatus.
Picture courtesy Corydoras world
Ian