Freshwater food fish (4)
(Other definitions for trout that I've seen before include "Food fish" , "one of a noted quintet" , "Swimmer" , "Fish - old harridan" , "It rises to fly" .)
'freshwater food fish' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for perch that I've seen before include "A fish; alighting place" , "Roosting place" , "Roost; old measure" , "Resting place for a bird and old measure" , "[SOMETHING FISHY]" .)
(Other definitions for pike that I've seen before include "Fresh-water fish or old spear" , "Fish - medieval weapon" , "Spearhead attached to a long pole" , "See 1 down" , "Position of one diving" .)