Does anyone give their children with ADD/ADHD a diet high in DHA Omega-3?

I have a wonderful little boy... who is fidgety, hyper, has a hard time focusing on anything, and throws the biggest fit I have ever seen when he doesn't get what he wants. I think he may have ADD or ADHD, however, I will not take him to the doctor for that and get him put on medication. Either way, I have heard that an increase in DHA in a childs diet can help a child focus better and behave a little better. I also heard that it can take a month or so for it to take affect. Do any of you see a difference in your child's focus since you started that in his/her diet?