It is essential that you get all the vitamins and minerals your body needs to function properly. Vitamin B12 is usually found in meat and dairy and you can get only minimal amounts from plant food. That is why you need to buy processed products such as soy milk and juices that are fortified with it.
You cannot get Vitamin A from fish, but you can eat plenty of vegetables such as carrots, pumpkins and squashes. These contain carotene which is converted to this vitamin inside the human body. The best way to get sufficient amounts of Vitamin D is to have frequent exposure to sunlight.
You have no choice but to have foods and drinks that are fortified with calcium. This is the only way in which you can get enough of this essential mineral. The good news is that you can get sufficient amounts of iron from nettle and spinach. The legumes and the raw nuts should also be present in your meals. These are rich in zinc and contain calcium and iron as well.
There are also meat alternatives such as the vegan meat products. Just search for best plant based meats on the internet.
Generally, it is important for your vegan diet to consist of as many different foods as possible.