Lake Ouachita is among 20 other bodies of water that are under a mercury in fish advisory in Arkansas.
This advisory only applies to those eating fish from Lake Ouachita.
It does not affect swimmers or boaters.
Health officials also say the advisory does not limit the use of Lake Ouachita as a drinking water source.
In other health news, a Chinese study shows that the practice called "moxibustion" can help with knee pain associated with arthritis.
It involves burning herbs and applying heat to certain body points.
Experts at Shanghai University of traditional Chinese medicine studied it on 110 people.
Participants were split into two groups: One was treated with moxibustion and the other got a placebo.
Patients who received the treatment three times a week for six weeks had a lot less pain and better movement.
You can find out more about the study in the Health Journal "Arthritis Research and Therapy"
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