small fry

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Small children.
• noun Young or small fish.
• noun People or things regarded as unimportant.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun One or more small or immature fish.
• noun informal One or more children.
• noun idiomatic One or more persons or things of relatively little consequence, importance, or value.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun someone who is small and insignificant
• noun a young person of either sex