whitefish

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

• noun Any of various freshwater salmonid food fishes of the genera Coregonus and Prosopium chiefly of North America, having a generally white or silvery color.
• noun Any of various similar or related fishes, such as the lake herring, whiting, or menhaden.

from The Century Dictionary.

• noun A general name of fishes and other aquatic animals which are white, or nearly so: variously applied.

from the GNU version of the Collaborative International Dictionary of English.

• noun Any one of several species of Coregonus, a genus of excellent food fishes allied to the salmons. They inhabit the lakes of the colder parts of North America, Asia, and Europe. The largest and most important American species (Coregonus clupeiformis) is abundant in the Great Lakes, and in other lakes farther north. Called also lake whitefish, and Oswego bass.
• noun The menhaden.
• noun The beluga, or white whale.

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

• noun Any of many fish.
• noun The beluga (both the sturgeon and the whale)

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

• noun any market fish--edible saltwater fish or shellfish--except herring
• noun flesh of salmon-like or trout-like cold-water fish of cold lakes of the northern hemisphere
• noun silvery herring-like freshwater food fish of cold lakes of the northern hemisphere