Then stop eating fish and meat, you can be healthy taking care of your environment and without killing any animal. Everything you are saying are still environmentally unfriendly options.
Sadly, this is an illusion. All agriculture is based on killing animals and distroying biodiversity, and if scaling to cover all population, would lead us to a world plenty of Fabian Tomasi.
Many vegetarians just take the choice to be blind to the huge problems with soy culture (for example), but those problems are not trivial at all.