pescatarian
Concise Oxford English Dictionary © 2008 Oxford University Press:
pescatarian /ˌpɛskəˈtɛːrɪən/
▶noun a person who does not eat meat but does eat fish.
– origin 1990s: from Ital. pesce ‘fish’, on the pattern of vegetarian.
'pescatarian' also found in these Oxford entries:

