One of the areas I do research in is fish contaminant uptake. Generally mercury toxicity concerns with fish are way overblown.
We have good reason to think high dietary selenium protects against mercury toxicity IIRC because mercury is harmful at selenium binding sites. Most open ocean fish regularly consumed have higher selenium levels then mercury with the exception of shark, swordfish, marlin, whale etc.
Even if that wasnt the case beef can have almost the same mercury levels as some commonly eaten fish like salmon.
The FDA limit of 1 ppm for human consumption was set with a safety margin in mind, and the only fish reaching that are swordfish, tilefish, shark, and the rare large tuna.
Meanwhile canned tuna is on average 0.17 for chunk light and something like 0.32 for chunk white. Canned sardines, salmon, etc. are about negligible.
Here in Hawaii many of us fresh ahi almost every day. The fish made into poke or whatever are usually large yellowfin or bigeye, higher mercury species but also high in selenium. And you don't hear about people needing to be chelated for Hg poisoning here.
I started this post saying concerns are 'generally' overblown. If you live near a polluted lake, you could probably dick yourself up eating Walleye every day is an example of an exception.
