"How do you get them to pose like that?"
Oh that's and easy one Lark: the Crucian has a piece of string that goes from its' pectoral fin around Neil's back and up to his left ear. So, when the Crucian flexes its fin, Neil smiles (thinly) and poses quietly for the camera.
That's right innit Neil?
You might not jealous Lark, but I most certainly am!