Any of numerous small food fishes

• Especially those caught with hook and line and not available on the market
• Perch, for example
• Bluegill or crappie

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1833, American English, from pan (n.1) + fish (n.).

Wikipedia Word definitions in Wikipedia
A panfish , also spelled pan-fish or pan fish , is an edible game fish that usually doesn't outgrow the size of a frying pan. The term is also commonly used by anglers to refer to any small catch that will fit in a pan, but is large enough to be legal. ...

WordNet Word definitions in WordNet
n. any of numerous small food fishes; especially those caught with hook and line and not available on the market

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
panfish \panfish\ n. Any of numerous small food fishes; especially those not available on the market. Any of numerous small food fishes taken with hook and line.

Wiktionary Word definitions in Wiktionary
n. fish that are suitable for cooking in a frying pan by virtue both of size and taste; '''panfish''' are caught primarily for eating, rather than for sport