ichthyarchyn.

/ˈɪkθɪɑːki/Etymology: < ichthy- (in ichthyo- comb. form) + Greek -αρχία rule, government.
1853 C. D. Badham (1854) 275 To back an Agnano..or Thrasymene ‘tenca’ against the whole of the Mediterranean ichthyarchy.
This entry has not yet been fully updated (first published 1899; most recently modified version published online September 2019).