Criticism for each returned fish (8)
I believe the answer is:
reproach
'criticism' is the definition.
(reproach is a kind of criticism)
'each returned fish' is the wordplay.
'each' becomes 'per'.
'returned' is a reversal indicator.
'fish' becomes 'roach' (roach is a kind of fish**).
'per' reversed gives 'rep'.
'rep'+'roach'='REPROACH'
'for' is the link.
(Other definitions for reproach that I've seen before include "Upbraiding, censure" , "Rebuke or criticism" , "Reprove gently" , "Express disapproval to (someone)" , "Scold(ing)" .)