>For example, according to the Torah law, the blood of an animal is forbidden to eat, but the blood of a fish is permissible. However, according to the principle of marit ayin, it is forbidden to eat the blood of fish as an onlooker may believe the blood being eaten is from an animal, and may thus believe that animal blood is allowed to be eaten.
There is a Jewish tradition, along the same lines:
>For example, according to the Torah law, the blood of an animal is forbidden to eat, but the blood of a fish is permissible. However, according to the principle of marit ayin, it is forbidden to eat the blood of fish as an onlooker may believe the blood being eaten is from an animal, and may thus believe that animal blood is allowed to be eaten.