Pescetarian is probably a neologism formed as a blend of the Italian word pesce ("fish") and the English word "vegetarian". The Italian word is pronounced [ˈpeʃe], while the English neologism is commonly /ˌpɛskɨˈtɛəriən/, with a /sk/ sound, thus differing from pronunciations of similar terms in English and Italian.
Pesce in turn derives from the Latin piscis, which has the form pisci- when it serves as a prefix, as it often does in scholarly terms (e.g. "pisciculture" /ˈpɪsɨkʌltʃər/ or "piscivore" /ˈpɪsɨvɔr/). Note that a piscivore, as a type of carnivore, eats a diet primarily of fish, whereas the neologism pescetarian refers to persons who consume plant derivatives as well as fish. A similar term is vegequarian.
Japanese nigiri-sushi. Many cultures offer pescetarian-friendly cuisine.
Concerns have been raised about consuming some fish varieties containing toxins such as mercury and PCBs, though it is possible to select fish that contain little or no mercury and moderate the consumption of mercury-containing fish.
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Similarly to vegetarianism, some pescetarians adopt the diet on the basis of ethics, either as a transition to vegetarianism, not treating fish on the same moral level as other animals, or as a compromise to obtain nutrients not found in plants as easily.
Eastern Orthodox Christians consume a variation of a pescetarian diet (allowing shellfish and mollusks without fish directly) on Wednesdays and Fridays throughout the year, as well as during Great Lent and the Nativity Fast (which in fact allows fish many days of the fast) and certain other fasting periods.Western Rite Orthodox are slightly more lax, requiring a stricter fasting period (single meal per day) but allowing a typical pescetarian diet as cited above. During fasting periods, dairy (whether eggs or milk-based product) is prohibited. In general, an Orthodox Christian diet uses a variation on pescetarianism approximately half the liturgical year. These usages are described in the Typikon, or Ustav, of each local Orthodox Church.
By contrast, Byzantine Rite Catholic Churches such as the Ruthenian Catholic Church have a set minimum of requirements for fasting, which includes eating fish, and an ideal fast described in Eastern Canon Law as permitting only shellfish, but not fish or other meat. Fasting periods vary widely; some churches, such as the Melkite Greek Catholic Church, have abbreviated the fast to start on December 10, following the Feast of the Conception by Saint Anne, reducing the fast to 15 days.[unreliable source?] The Melkite Greek Catholic Church permits meat on Saturdays, Sundays, and certain feasts, all of which are not treated as fast days. The Melkite Church describes three levels of fasting: The Law - "That which is required", The Tradition - "That which the devout follow", and Customary Compromises.
In general, Eastern Christian (whether Orthodox or Catholic) monks eat no meat, but outside the aforementioned fasting periods, will consume dairy (except Wednesdays and Fridays, and in some cases Mondays).
By tradition, most Hindu Brahmin communities follow a strict lacto-vegetarian diet. However, there are a number of Brahmin sub-groups that allow fish eating. These include the Goud Saraswat Brahmin community from Coastal South-Western India. This community regards seafood in general as vegetables from the sea. They refrain from eating any land based animals. Other Hindu communities who consume seafood in great quantity are the Maithili Brahmin and the Bengali Brahmin. The latter also eat meat on special occasions.
Comparisons to other diets
Pescetarianism is similar to many traditional diets emphasizing fish as well as fruits, vegetables and grains. Many coastal populations tend to eat this way and these features characterize the traditional Mediterranean diet and the diets of many parts of Asia, Northern Europe, and the Caribbean. These traditional diets tend to also include meat although it is peripheral. In common with some vegetarians, pescetarians often eat eggs and/or dairy products, in addition to fruits, vegetables, nuts, and grains.
Pescetarians are sometimes described as vegetarian or pesco-vegetarian, but vegetarians commonly do not consider the pescetarian diet to be vegetarian. For example, the Vegetarian Society, which initiated popular use of the term vegetarian as early as 1847, does not consider pescetarianism to be a vegetarian diet. The definitions of vegetarian in mainstream dictionaries sometimes include fish in the diet.