I have been a vegetarian for over 30 years. As far as the definition that I understand, salmon and tuna are not considered vegetarian (nor is any meat, fish, or fowl).
People who eat fish, are more accurately called peacatarians. The reason why, is because it causes less confusion. I can’t begin to count the times when I am at a restaurant or at someone’s home, when they find out that I am a vegetarian, then they ask, “But you eat fish, right?” No. Fish are live animals. They are not considered part of a vegetarian diet.
I don’t care what people eat, but claiming to be a vegetarian, while also eating fish, just causes a lot of confusion.
In general, vegetarians can and do eat eggs and dairy, in addition to vegetables, and fruits, and grains, and fungi. Basically, food that does not involve killing animals (including not killing fish, which are animals). I also forgo purchasing or wearing leather, or any other products that involve the killing of animals.
Vegans go a few steps further by shunning the eating of any “animal products” including eggs, dairy, and sometimes honey (made by bees) and some sugar (usually sugar made from sugar cane, as opposed to sugar beets, which is often filtered with animal bone char) and products containing gelatin (which is rendered connective tissue of animals).
The biggest misconception about vegetarians, is that they have a difficult time getting enough protein. That simply isn’t true (and most people, vegetarians or not) get way too much protein. It is also a misconception that vegetarians need to eat multiple types of “incomplete” proteins at the same time to get the correct amount of essential amino acids. That’s not quite correct. You can read all about that here: https://www.forksoverknives.com/the-myth-of-complementary-protein/
Another myth about vegetarians is that they are sickly. That just doesn’t seem to pan out. I’m one of the most healthy people I know, and vegetarians are less likely to develop obesity-related diseas such as certain cancers, heart disease, and diabetes, as long as their diet is mostly whole foods.
Another myth is that most vegetarians are thin. Some are, but there are what I like to call “Cheetos Vegetarians”. Those are the folks that eat vegetarian food, but mostly of the highly processed variety, with too much salt, too much fat, too much sugar, and barely any fiber. Potato chips are vegetarian.
Another myth is that most vegetarians are patchouli wearing, unwashed hippy types of people. Neither me, or any of my vegetarian friends fit into that category. We are all quite different, but the main thing that binds us together (I’m speaking only of my friends) is a desire to take care of animals, and leave a smaller carbon footprint, and as a byproduct, be more healthy.
Another myth is that vegetarians make it their mission to shame non-vegetarians, or to act as though they are “holier than thou”. Some people do that, but I don’t, and neither do any of my friends. I love to cook, and I love to create recipes, and share recipes, and talk about food. If people are curious about what it’s like to be a vegetarian, but I don’t push it on anyone, and it is not a topic of every day conversation.
Another myth about vegetarian food, specifically, is that it is bland, boring, and unsubstantial. It can be, but so can meals that contain meat. Most of you guys already know that I love to cook, and that I am a very adventurous eater, and that I can show you a million delicious recipes.
Another myth is that eating vegetarian food is expensive. It can be if you go out to eat a lot, or shop exclusively at Whole Foods. I buy a lot of things, especially produce, and healthy snacks, and some frozen foods at The 99 Cent Only Store (me and out dearly departed Ibstubro used to compare delicious products we had found there, and at Big Lots). I also shop at our local grocery store, our local Farmers Market, and Trader Joes. Whole Foods is wonderful, but I only shop there, very rarely.
Also, when I eat out with family, or non-vegetarian friends, we almost never eat at Vegetarian or Vegan Restaurants (I save those for my outings with my veg friends). As long as there is something I can eat, I’ll eat at just about any restaurant anyone wants to go to. Two places that I avoid are McDonald’s and Applebees, which are not vegetarian friendly. McDonald’s has a lettuce salad, and French fries, not much of a meal. Applebees has virtually no vegetarian options, at least not the last time I went to one about 5 years ago. Even the salads all had chicken or bacon. The last time I went there, I requested that the bacon be left off of my salad. It came with bacon all over it : (
I do have to ask questions when I eat at “regular” restaurants, because there is often beef broth, or chicken broth, fish broth, fish sauce, or bacon, or chunks of meat, or gelatin lurking in soup, salads, salad dressings, sauces, rice dishes, pasta dishes, and desserts.