I think that's an opportunity to educate, not an opportunity to invent more and more new terms.
I actually don't mind pescetarian for someone whose only meat consumption is only fish. I knew someone online who called herself vegetarian but ate fish. After I explained to her the issues this could cause for actual vegetarians, she adopted pescetarian instead.
Then I've seen people who eat only fish calling themselves aquarivores.
Wtffff. The existing term wasn't good enough for them? They needed to feel special by inventing a new word? If they go to a restaurant, how confused will the wait staff/chef be when faced with all these terms? We can't even agree on a term amongst ourselves, no wonder restaurants can't get it right.