daivid
1
οἱ τοίνυν ἰχθῦς, ὅταν παρίωσι, προσνέουσι τοῖς πουλύποσιν ἀδεῶς, ὡσεὶ πέτραις.
The context is that cuttlefish lie in ambush for fish. This line makes sense to me with ἰχθύες but not if it really is ἰχθῦς.
I would assume some typesetting error but given my level of Greek I exclude some huge misunderstanding on my part.
bedwere
2
Dictionary comes to the rescue.
Both forms are attested. Basically ἰχθῦς is a contraction of ἰχθύες
Pros
3
ἰχθυηρόν τι κύκλῳ γίνεται ἐνταῦθα. 
daivid
4
Seems I was right on both counts
-It needed to be nominative
-I had got something fundamental wrong
Thanks very much for sorting it out.