A small fish or a young, immature fish.
From 'fish' + '-let' (diminutive suffix from Old French, meaning small), similar to 'piglet' or 'booklet,' indicating something small or juvenile.
This charming word is rare in modern English but appears in older literature and still survives in some regional dialects—fishermen might affectionately call small fish 'fishlets,' and the suffix '-let' itself is a relic of how English creates cuteness and smallness through sound.
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