It seems there should be an existing topic and there are a few although not as focused as your topic, so combining them might make this one too wide so I just merged one above that seems relevant and include some links below.
Anecdotally some help some people but not all people. I found quality krill got me off a cane and able to play tennis for example. For many krill was reported as a waste of their money. Glucosamine, glucosamine and chondroitin, and tumeric also have proponents.
This site should not be taken as authoritative, but seems to have a decent overview of a range of supplements claimed by some to help arthritis. Curiously krill is not included.
I expect others will add resources from medical research through to more anecdotal personal experiences and opinions.
