is "cod liver oil" similar in *value?

Probably. You may need to check the label.

Here's where it gets technical. The active ingredients are the two poly-unsaturated fatty acids DHA and EPA, standing for "dodeca-hexa-enoic acid" and "eicosa-penta-enoic acid" (which is why we call them DHA and EPA). The total of those two should be 1000 mg/day, whatever number of pills is needed to get there or higher, and whichever fish oil you choose. Flaxseed oil should do, too, if the numbers add up.

Oh, and BTW, if you eat fish three times a week you're already getting your quota!

PS: for any linguistically-inclined people who might happen to be among us - DHA has twelve (dodeca-) carbon atoms and six unsaturated carbon=carbon bonds (hexa-ene) and EPA has eleven and five, respectively. Notice that it's eicosa- eleven, not icosa- twenty! The "-oic acid" is what identifies them chemically as fatty acids rather than fats.

edit: Harrumph. See below.