My almost 2 year old male malamute is starting to get snappy with little dogs who run up to him. Would appreciate any advice on when best to get fixed and if advisable to let him stud once first. No negative comments please just want whats best for my dog.

Neither will help in this situation.
If he is used his behaviour could change for the worse or it might not change at all but it won't improve his reactions to other dogs 
You need to seek a balanced trainer to assess him to see what is causing him to react, if fear then castration is not a good idea either. It sounds like other dog owners are not having control of their dogs, no dog should be running up to another without your permission but sadly it happens.
Is your boy on or off lead when this happens? Is it certain breeds? Does location make any difference or time of day?

It is almost impossible over the Internet to say why he is doing this, it needs someone with the right qualifications to watch him in action. It could just be a training matter or it could need a behavioural management plan.

Advice from the FAQ

Should I use my dog at stud?

Absolutely no, on both counts.   Allowing him to mate will probably make this aggression worse plus he'll be looking for the next bitch to mate with.  

The only guarantee with castration on the other hand, is no puppies which provided he's properly housed, shouldn't ever happen unless planned. 

I'd echo what Suejaw has said.   He may well be adopting an attack is the best form of defence attitude, with other dogs.   It's a pity that the owners of these dogs allow them to run up to your dog.

Agree with all.that has been said and yes it's a shame so many adopt the my dog is only being friendly and allow this to run up to yours.  Castration is unlikely to improve the situation
I have one who is nervous agressive around other dogs and it  can be very hard when out and about.
I took advice from a good reward based behaviourist who idemtified that it was because she was nervous and explained how best to manage it . 
For now until u have advice in person  I would keep him on a lead and try and walk where others arnt likely to be .lots of treats to distract and trying to be extra alert to avoid situations if at all possible
  Or find a secure dog walking field that u can have on your own .Long term that has been my solution  U don't want your dog to have to practise his behaviour

> little dogs who run up to him

Why are little dogs running up to him?

They are in the wrong, not him. You might want to have a read of this great article by Suzanne Clothier: https://suzanneclothier.com/article/just-wants-say-hi/

Frankly, if I couldn't walk down the street without complete strangers running up to me and hugging me, I'd get a bit angry with them as well....

Why are little dogs running up to him?

This seems to be getting worse at the moment. I think many of the impulse puppy buyers fall into the ‘he only wants to play brigade’ who also think a puppy trains itself. It’s not fair on other dogs. My boy hates other dogs running up to him and invading his personal space, especially wiggly cockerpoo types as I don’t think he can work out which end is which! If they mind their own business he’s fine, but it’s taken a bit of effort to get to this stage.

A wee quibble though, I’m not keen on neutering being referred to as being ‘fixed’ as though this is the solution to all problems, and as others have said, it can make things worse.

It also implies that entire is somehow 'broken', where it is the opposite really.

Tends to be a more American term than British ive found

I don’t think he can work out which end is which!

off topic but some 40ish years ago I had a cocker/lab who was totally laid back with all dogs - pups and adults. Just going round a corner she came face to face with an OES and had a blue fit for this reason