The Sea Fisheries Institute - National Research Institute conducted research on the presence of undesirable substances in marine and farmed fish. Scientists found that in species imported from Vietnam and China, including tilapia meat, a higher concentration of lead was detected compared to other fish.   But that's not all. The tilapia also contained mercury and cadmium, experts say, albeit in low quantities. To add insult to injury, scientists from Wake Forest University have shown that the ratio of omega-3 and omega-6 fatty acids in tilapia meat is very unfavorable (too little of the former, too much of the latter). What can be concluded from this? "Such a combination can potentially be a dangerous source of diseases for patients with heart disease, it can also foster joint inflammation, be a factor causing asthma and other allergic and immunological diseases"- comment on the results of the research scientists for sciencedaily.com.  Click here to continue this story.