Thats not true. Oyster is a very low mercury seafood.

https://www.fda.gov/food/metals-and-your-food/mercury-levels-commercial-fish-and-shellfish-1990-2012

A great way to approximate mercury levels is "how far up the food chain is it?". Tuna is at the top and very high in mercury. Sardines are very low. Oysters are too.

edit: you will reach zinc overdose about 20x faster than you will mercury overdose. So eat a 3.5oz/100g can of oysters once a week and you are fine. Eat more than that and you get zinc overdose. Eat 21x cans and you get mercury overdose. I had zinc overdose once and it made my calf muscles twitch. I ate a tonne of tuna once and I had a floater in my eye. The leg cramp went away in a day or two. The floater took 2 years to move to a different part of my eye or disappear.

Thats not true. Oyster is a very low mercury seafood.

https://www.fda.gov/food/metals-and-your-food/mercury-levels-commercial-fish-and-shellfish-1990-2012

A great way to approximate mercury levels is "how far up the food chain is it?". Tuna is at the top and very high in mercury. Sardines are very low. Oysters are too.