I suspect some might, but you can get omega 3 oils from linseed oil as well as from fish, and I expect that vegetarians would try to get their omega-3's from a plant based oil rather than an animal based oil.

They use seaweed in it's place for it about the same in health reasons.

Most vegetarians won't eat fish so it's highly unlikely they'll eat fish oils. Another source of omega 3 fatty acids is flaxseed oil. Flaxseed oil is the best plant source for omega 3 fatty acids. You can also eat chia seeds, which are also high in omega 3 fatty acids and fiber. For more information on flaxseed oil: http://www.healthy-oil-planet.com/flaxseed-oil.html

1) No. "Vegetarianism is the practice of a diet that excludes all animal flesh, including poultry, game, fish, shellfish or crustacea, and slaughter by-products." Source and further information: http://en.wikipedia.org/wiki/Vegetarian 2) "A lacto-ovo vegetarian is a vegetarian who does not eat beef, pork, poultry, fish, shellfish or animal flesh of any kind, but is willing to consume cheese, butter, yogurt and eggs. Lacto- means "milk" and ovo- means "egg". In the Western world lacto-ovo vegetarians are the most common type of vegetarian. Generally speaking, when one uses the term vegetarian a lacto-ovo vegetarian is assumed. Lacto-ovo vegetarians are often well-catered to in restaurants and shops, especially in Europe and metropolitan cities in North America. Some lacto-ovo vegetarians who are motivated by ethical reasons may avoid fertilized eggs as well as caviar, feeling that both involve the killing of beings or torture and exploitation of source animals. They avoid cheese that contains rennet and yogurts that contain gelatin as these two things involve killing. In contrast, a vegetarian who consumes no animal products is called a vegan." Source and further information: http://en.wikipedia.org/wiki/Lacto-ovo_vegetarianism 3) "Fish oil is oil derived from the tissues of oily fish. Fish oil is recommended[citation needed] for a healthy diet because it contains the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), precursors to eicosanoids that reduce inflammation throughout the body However, fish do not actually produce omega-3 fatty acids, but instead accumulate them from either consuming microalgae that produce these fatty acids, as is the case with prey fish like herring and sardines, or, as is the case with fatty predatory fish, by eating prey fish that have accumulated omega-3 fatty acids from microalgae." Source and further information: http://en.wikipedia.org/wiki/Fish_oil

Depends on the type of vegetarian. Vegans won't. Pesco-Vegetarians will. For vegans (no animal product at all), flax seed oil is a good replacement.

Some will, I don't. Personally my personal ''rule'' is that I don't eat meat (or fish) unless it's for medicinal purposes. If I needed fish oil capsules I would happily take them. A vast amount of prescription medicines and vaccines contain animal derivatives in some form, even if it's just gelatin in the capsule.