Many of the fish oils on the market are basically generic combinations of any variety of fish that typically have 180 mg of EPA and 120 mg of DHA (the two main Essential Fatty Acids found in fish oil) per gram (typically 1 softgel). The problem with those is that most of them don’t tell you what type of fish is used (i.e. what the source of the fish oil is). This not knowing poses a problem for some people. For those that want to know the source of their fish oil, they may opt for specific options like Salmon Oil or Cod Liver Oil.
Salmon is considered one of the “cleaner” fish that typically live in cleaner waters like those around Norway (which is a common area to get Salmon Oil from). It has a different ratio of EPA to DHA where it’s normally in almost equal amounts and it can also be found as “Virgin Salmon Oil” (which uses less processing).
Cod Liver Oil is quite a different option by comparison, as it is from the Cod’s liver instead of the general body fat. One important difference here is that the Vitamin A and Vitamin D content is stored in the fish’s liver. Some people aren’t able to take the extra doses of the vitamins that come in the Cod Liver Oil if they take certain multivitamins, but some prefer the extra vitamins if they don’t get enough of those fat-soluble vitamins on a regular basis.
One nice thing about most all fish oil products on the market is that it’s basically industry standard for quality that fish oil should be molecularly distilled to remove any trace contaminants of any heavy metals. Because of that, consumers can be assured that there wouldn’t be any sufficient levels of Lead, Mercury, PCBs, or other contaminants that cause concern.