Not a daft question at all if you've never heard of it 
Well sort of like that, but I suspect rather than sex, its more a case of two species spawning in the same area who's genetics allow cross fertilisation. Say from Roach to Bream, which I believe is common.
The mouth detail isn't to clear,
(use the Macro facility on your camera Al, if you're going to try turning minnows into monsters)
But first impressions are that it's a small Rudd.
If not,how about a Bitterling.