Can Skinless Salmon Be Assumed To Be Kosher?
Shailoh of the Week by Rabbi Zvi Nussbaum
Rabbinic Coordinator, Kosher Hotline Administrator for the Orthodox Union
The general rule for skinless salmon:
Although kosher fish are usually identified only by the presence of scales, the Orthodox Union (OU) has a long-standing policy of accepting as kosher all reddish-pinkish fillets, even without a piece of skin by which the fillet can be identified. The basis for this policy is that there is no fish that has a reddish-pinkish flesh underneath its skin except salmon, trout, and possibly some carp, which are all kosher fish.
One concern is the use of an artificial vitamin supplement designed to redden the flesh of farm-raised salmon. The basis for the OU policy of accepting all reddish-pinkish fillets as kosher comes from Rabbi Yisroel Belsky, z”l, in the name of Rabbi Moshe Feinstein, zt”l, that a fish fillet with a reddish-pinkish color could be accepted as a siman-muvhak (an absolute sign) of kashrut, if one could be reasonably certain that no non-kosher reddish-pinkish fleshed fish exists in nature.
Rabbi Feinstein’s psak (ruling), however, could only apply to fish whose flesh is naturally red, such as wild salmon and trout. The flesh of the farmed varieties of these fish would (if not for supplementation) be a sickly pale-white. The reason for farmed salmon’s natural absence of redness is a lack of astaxanthin, an antioxidant that wild salmon and trout absorb from their diet of lobster, shrimp, krill, plankton, and algae.
Only salmon and trout retain natural carotenes in their reddish-pinkish flesh. Only fish that have the ability to store natural carotenes in their flesh can retain artificial carotenes, such as DSM’s astaxanthin “Carophyll-pink,” in their flesh. Other fish are not red because they do not store carotenes whether natural or artificial, in their flesh.
The OU Poskim maintain that red flesh is still a siman muvhak for a kosher fish, as only salmon and trout have red or pink flesh, and that the OU policy of accepting reddish-pinkish fillets without the skin is justified.