tiddler

 
Pronunciation: /ˈtɪdlə/

noun

British informal
  • a small fish, especially a stickleback or minnow.
  • a young or unusually small person or thing: she was only a little tiddler, ten years old

Origin:

late 19th century: perhaps related to tiddly2 or tittlebat, a childish form of stickleback