I am a vegetarian, but lately, I have decided to incorporate some fish into my diet, about 2-3 servings a week of healthy Tilapia, Cod, Salmon, and such, just to incorporate some healthy vitamins and fats into my diet naturally, and not just through supplements and fortified foods. So I would possibly be labeled as a Pescetarian, which is a vegetarian who also eats some fish.
Just to be clear, I am not a huge fan of fish, and if you can find it, there is vegetarian fish replacements (although idk how they taste), but I decided to go for it because of the health effects of fish, such as fish’s protective effect against bowel cancer. The FDA and AHA themselves claim that you should consume at least 2 servings of fish a week, due to the health effects they have. A Pescetarian diet is at LEAST as healthy for you as a lacto-ovo vegetarian diet.
Other than the occasional fish, I eat mostly beans, spinach, legumes, broccoli, peppers, etc, and try to limit my intake of dairy, while almost completely eliminating eggs from my diet. Or for a shorter phrase, a semi-lacto pescaterian. It is better to reduce egg consumption due to the negative health effects a large amount of eggs have, or at least limit yourself to egg-whites if you have to have eggs.
But based on the evidence, I see nothing wrong with a moderate pescearian diet. Just one Tilapia fillet (about 4 oz of fish) has only 110 Calories, 2 grams of fat, only 360 grams of sodium, and a whopping 21 grams of protein! One fillet also has a LOT of B12, Vitamin D, and selenium. One 4 oz fillet of Pollock has even more B12 and Selenium than Tilapia, with even less sodium, less fat, and only 100 Calories. These fish also have a decent amount of Omega 3’s, and can easily be incorporated into a healthy plant-based diet. But if you don’t want to, that is OK as well, you can easily get Omega-3’s through plant-based sources, such as Flaxseed.
But as far as I can tell, it is very easy to incorporate small amounts of fish moderately into an otherwise 99% vegetarian diet high in leafy greens, nuts, seeds, legumes, beans, whole wheat breads, and the like. And it is not expensive either, I got 4 4oz fillets of Tilapia, and 3 4oz fillets of Pollock for a gran total of less than 7 bucks at my local Kroger, and that will last me about a month of eating fish.
The best advice I am going to give is this: Moderation. But according to the evidence, you should be able to eat a really healthy pescetarian diet with little issue. It is also MUCH healthier than the average carnist diet.