Could someone help me with any information on mating my 11 month old chihuahua dog. He is lovely but is starting to get aggressive with everyong as he is so frustrated

Breeding will not make him any better...it could make him worse.An aggressive dog of any breed should NOT be bred from
Archer

I think neutering and training would be better avenues that trying to possibly pass the aggression onto potential offspring. There are lots of people on here who are experienced with training dogs and should be able to point you in the right direction.
Emily

Can you describe why you think he is aggressive, do you mean he is threatening people or trying to bite? If so he needs training and may be you need help to sort the problem, breeding him would be the height of irresponsibility if the poor temperament is inbred and not caused by some health problem.

Start by having the vet check him over to make sure he is fit and well then if you can't control his behaviour then ask the vet to recommend a trainer to you or pick one from the apdt list here