Semi-vegetarianism means eating seafood or poultry, or both, but no red meat. People who eat red meat on rare occasion are flexitarians. Real or semi-vegetarians, though, usually resent flexitarian, looking down on this term and calling it cheating.
A pescetarian is a person who eats fish, shrimp and seafood. They do not eat poultry.
Pollo-pescetarians eat seafood, shrimp and poultry but no red meat.