IPA: /ˈmɪltər/
KK: /ˈmɪltər/
A male fish that is prepared to reproduce.
The milter swam upstream to find a mate during the breeding season.
The word 'milter' originates from Old English 'milt' (meaning a soft or tender part) and the suffix '-er' (meaning a person who). A milter is a person who deals with or is associated with the soft or tender parts, often in the context of fish or other animals.
Think of someone who works with the 'soft' parts ('milt') of fish or animals, and the '-er' indicates that this person is involved in that activity.