Simply put, the common fish ball, which can also be spelled fishball, is an edible, ball-shaped patty made of pulverized fish. These fish meatballs are primarily white or yellow in color, and measure about an inch to two inches in diameter. They are made by pounding rather than grounding, and have a very different texture to Western meatballs.
These balls are a staple of Chinese cooking and are used in a wide array of dishes. In the US, they are available in most Asian groceries. They are also hugely popular in Singapore, Malaysia, Taiwan, China, and the Philippines.
While cooking a fish ball is pretty straightforward - done by frying or boiling - the way it is enjoyed varies greatly from one country to another. People from Hong Kong, for instance, differentiate between two kinds of fish balls. One kind is eaten with noodle dishes, while another, more yellow kind is sold in "strings" or skewers in food stalls.
In the Philippines, locals not only have fish balls, but squid balls as well. These seafood balls are sold skewered on bamboo sticks and dipped in various sauces as street food. The deep fried fish is enjoyed as a snack and is very popular. Fish ball stands in this country seem to operate in much the same way a hot dog stand does in the US.
In Singapore and Malaysia, fish balls are used just like any other seafood and may be found in soups, noodles, and served with rice. They are also sold in hawker stalls. They even have versions that have been filled with pork, which are called fuzhou fish balls.
It is interesting to note that a non-Asian kind of fish ball also exists. They can also be found in Jewish cooking, more specifically in the Ashkenazi Jewish community, where it is called gefilte fish. Traditionally, the mixture that makes up the gefilte fish was stuffed back into the fish before serving, and was not made into balls. Nowadays, however, the mixture is sometimes made into patties or balls and served with a horseradish sauce. Unlike its Eastern counterpart, and more in line with Western methods, the gefilte fish is ground, not pounded. The fish meat is also combined with other ingredients, such as carrots, eggs, etc.