Do animagi get to choose their form?

[clcb58]

No: HPFGUIDX 168151

Hi all,

New to the group here -- I've been enjoying the discussions.

I wonder if a wizard who learns to become an animagus gets to choose what animal they 
transform into or do they just get what they get, like with a Patronus? 

If they get to choose, I wonder why Peter Pettigrew would have chosen a rat that Sirius' 
dog could've eaten?

I can't find anything in the canon about this, so I know everything will be speculation, but 
I'd love to read your thoughts.

Thanks,
clcb