Best age to castrate Bullmastiff if at all?

Hi I was wondering on peoples experiences when is the best age to castrate my bullmastiff. He is currently 17mnths old and hasn't shown any behavioural problems. He is calm and very friendly, the only time i have heard him grumble was when another dog kept growling at him but would'nt leave him alone! Is his personality pretty much now, how it will stay or is still likely to develop any aggressive issues with other males? He has been well socialised from a puppy and has many doggy friends he meets out on walks. We have 4 other dogs, a spayed bullmastiff and min pin (who rules the roost!) and a neutered collie x and greyhound, they all get along fine and Dexter (bullmastiff) respects them as they are all older. My only issue with getting him neutered is that his mother we have found out is very nervous (long story) and I have been told that taking away his testosterone could bring out any nervousness in him? Sorry for the long post

To cut a long story short, if it aint broke why fix it?

If there are no overwhelming environmental reasons (eg unspayed bitches, unfenced gardens) or training issues (dog goes roaming on his own) then personally I see no reason to neuter him.

Whilst neutering can prevent SOME health issues it can INCREASE the likelihood of others, so you need to weigh up all the pros and cons.

In a breed such as yours where complete growth is not attained before 3 I would delay it as long as I could in any case.

i have just had a eureka moment. i have a bullmastiff who was a little nurvouse as a puppy but quite outgoing and friendly. She was spayed at 18 months old and she turned in to a nervouse wreck at around 2. Had never put the 2 together till now i wonder if that is why.

As for your dog - im very pro spray but i dont actually have a reason for this as ive never given it much thought just knew i would never breed phoebe. You need to make the decision for your self you can alwasy have it done at a later date