Rheumatoid arthritis is a form of arthritis that causes pain, swelling, stiffness and loss of function in your joints. It can affect any joint but is common in the wrist and fingers. Rheumatoid arthritis is different from osteoarthritis, the common arthritis that often comes with older age. Rheumatoid Arthritis can affect body parts besides joints, such as your eyes, mouth and lungs. it is an autoimmune disease, which means the arthritis results from your immune system attacking your body’s own tissues.
No one knows what causes rheumatoid arthritis. Genes, environment and hormones might contribute. Treatments include medicine, lifestyle changes and surgery. These can slow or stop joint damage and reduce pain and swelling
My expertise is in the natural product field, I have no medical training (although have a daughter a pharmacist) so am not qualified to talk on the research on medical drugs. However a paper called Cutting Edge Treatments (link given in the resource box) may give you some information on pharmacy type treatments. My only worry with them is the side effects, particularly as they effect on heart attack / strokes.
Looking at natural products there are a wide range of herbs and spices touted, some limited evidence for some but none I would personally recommend. However Omega 3 fish oil is a different matter. All properly randomised and double blinded trials I can find show positive results. While it will not cure the disease it appears to delay the progression and give pain relief. This pain relief often allows a reduction in the prescribed drug regime. A summary of some of the fish oil research called Fish Oils and Rheumatoid Arthritis is also given in the resource box.

The amount of fish oil needed to achieve the research results is quite high. Much higher than that needed to get the heart and brain benefits that the fish oils confer. It would seem to me that 3-6 capsules daily are needed and it would take some 12 weeks for the effects to be felt.

One of the reasons that Omega 3 (EPA/DHA) work is that our modern diet contains far too much Omega 6 and this causes inflammation. Some research indicates that the current ratio in the Western World is in the order of 25 to 1. Early in our development it was closer to 1 to 1. The supplementation by Omega 3 combats and reduces the negative effects of the excessive Omega 6.
Also important is the EPA/DHA ratio. In all common Omega 3 capsules found in our health food shops and pharmacies the EPA is 18% and the DHA is 12% (this is either from North American salmon oil or South American sardine oil). This is also the ratio used in most research as it is the common standard fish oil and can be produce very cheaply.
However the more important one of the two in heart and brain health is DHA and another paper “Why Fish Oils help with Conditions like Rheumatoid Arthritis” also given in the resource box indicate that this may be true in Rheumatoid Arthritis as well.

References
http://www.oilofpisces.com/rheumatoidarthritis.htm
http://www.arthritistoday.org/conditions/rheumatoid-arthritis/ra-treatment/rheumatoid-arthritis-treatments.php
http://www.sciencedaily.com/releases/2009/10/091028142227.htm
http://www.seniorhealthcare.co.nz