Hi there
We're vegetarian, so my 3 1/2 year old and 1 year old have never yet had fish or meat both are (mostly) happy and healthy!
Meat substitutes like quorn are fine, but they are low in calories and high in fibre, whereas babies need calories/fat and shouldn't have too much fibre because it can cause foods to rush through their system without the goodness being absorbed. I offer meat substitues like quorn mince or soya sausages maybe once or twice a week, but neither of them are all that keen!
The rest of the time they get their protein etc from dairy (milk, cheese, yoghurt etc), eggs, peas, beans, humous, and occasionally lentils, coconut milk, nut butters.
If you're not offering meat/fish, you should also offer foods that are high in iron spinach/greens, peas, dried fruit, tomato puree, breakfast cereal etc. Fruit and fruit juice containing lots of vitamin C to help absorb the iron if served at the same time.
Hope this helps!
BG xxx