IMO, Why take the risk of taking in more mercury, even in "moderation"? when there are supplements with not only low mercury fish oil contained, but the oil is then tested/purified.

I tried sardines because of the low mercury and Im pretty sure I had effects from that. Similar to what happened when I started having kelp mixed with ocean sea salt. Nothing dramatic, but certainly something and I didn't feel comfortable continuing it.

I got no such effects from molecularly distilled fish oil, but rather appeared to gain some benefits.

Each to their own though. Perhaps I am really hypersensitive to toxins/metals and I have to be extra careful. I'd just be careful because the last thing you want to do is take in any mercury whilst you're attempting to detox it.