Here is a table showing the peroxidation index of various oils and comments from our dear fiend Bruce K.
This measures the total double bonds, so saturated fats have a lower peroxidation index and fish oil is twice as high as flax oil. Flax oil is 32 times higher than coconut oil, meaning it has about 32 times as many double bonds. Butter as about 2.6 x as many double bonds as coconut oil. Cocoa butter and beef tallow have 5-6 times as much as coconut oil.
There is one thing in this index that I disagree with. When you get to the 5th double bond, they add 50% to the peroxidation index, where it was double for the first 4 double bonds. The 6th double bond only adds 33% to the peroxidation index. I believe this underestimates the instability of fish oil. The 5th and 6th double bonds should double the peroxidation index, Instead they only increase it by 3/2 and 4/3.
And I would use no more than 1 ml = 1/5 tsp = 1g of fat. This amount should be enough if other dietary factors were also optimized. An adult doesn't need more than 2g of the raw fermented high-vitamin cod liver oil. Maybe 4g for growing children and pregnant/nursing women. It would be better for every one if they just got more sun and avoided things that will deplete the body of vitamins.