A Codex MRL is the maximum concentration of (pesticide) residues intended to be legally permitted in or on food commodities and animal feeds. For organochlorine pesticides (OCPs), the MRL values set forth by the Codex Alimentarius Commission are on fat basis for meat other than marine mammals, just like those provided by the European Commission. Since OCPs tend to concentrate and stay in fatty tissues, and upon proper adjustment for fat intake from fish, either the Codex’s or the European Commission’s MRLs may be used with caution to set health advisories or even legal actions. It is perhaps based on this notion that some POC residues in fish are still reported on fat basis in the literature.