Gehakte (chopped) or gefilte (stuffed)? Meat-mincer or chopping knife? Sweet or savory? Most interviewees agree that fish tastes better when chopped by hand, but they differ on whether to add sugar or pepper to the recipe. This distinction goes deeper than simply being a matter of personal preference - scholars have discovered that there are discrete geographical areas in which each type of fish is prepared.
The "gefilte fish line" (shown in blue on the map on the left, adapted from Steven M. Lowenstein's The Jewish Cultural Tapestry: International Jewish Folk Traditions, 2000), which divides the sweet (west of line) from the savory (east of line) regions of Europe, happens to trace almost precisely the line that divides the Central Yiddish dialect (spoken primarily in the region corresponding to present-day Poland) from the Southeastern and Northeastern dialects (spoken primarily in the regions corresponding to present-day Ukraine and Lithuania/Belarus, respectively). The dialect divisions are indicated on the map with a red line, adapted from Meyer Wolf's "The Geography of Yiddish Case and Gender Variation" in The Field of Yiddish, v. 3, 1969. As the Yiddish linguist Marvin Herzog, among others, has noted, "sweetened fish, also called pojliše fiš "Polish fish", is generally unpalatable to those east of the indicated [dialect] border, who prefer their fish seasoned only with pepper" (The Yiddish Language in Northern Poland: Its Geography and History, 1965).
The map on the right shows present-day Ukraine, and the towns in which recipes were collected by AHEYM are marked in different colors. (Zoom out for a better view.)