I met a pescatarian on a flight one time. The guy didn't know much about fishing, but it was the only meat he ate.
at least he did not call himself a vegetarian like many do. last i checked, fish was meat like you said.
My sis was a vegan and got sick and anemic. now she eats fish 2-3 times a week and is better. a very hard diet to keep up with and get proper nutrients.
I would take a b-complex, fish oil (i know it comes from meat but where will you get DHA and EPA?) and D3. i bet there are more you just cannot get from a vegan diet.
or "go all in" on a pescatarian diet?