Duck breed assistance please!

[Rudies Roost]

Duck breed afficionados...can anyone please assist with what this silver/grey duck's breed may be? I bought it with a pair of Swedish Blacks, it was kind of a "free extra". It was sold as a duck but I've never heard it quack and it's pretty happy biting my legs and chasing me up the garden so, unless anyone can tell me otherwise, I'm assuming it's a drake. Any help would be appreciated...also any advice other than sitting on the drakes to stop there aggression? It's driving me mad now!

The picture isn't the best, it's all I have for now, the SB is on the left and the white on the right is one of my Cherry Valleys. ..please help!

 

[Allears]

Can't help with the identification, but great photo of colour progression

 

[Amiga]

@Rudies Roost I have seen some references that indicate that there are offspring from Swedish blacks that look that silvery blue gray color I see in the photograph.

https://en.wikipedia.org/wiki/Swedish_Blue

 

[Rudies Roost]

Can't help with the identification, but great photo of colour progression

Ha ha! Well spotted...I hadn't noticed, but I'll take credit for that!

 

[Rudies Roost]

@Rudies Roost
  I have seen some references that indicate that there are offspring from Swedish blacks that look that silvery blue gray color I see in the photograph.

https://en.wikipedia.org/wiki/Swedish_Blue

Many thanks for the useful info..appreciate it