Why 膾(회) and not 鱠(회)?

The Chinese character for "sliced raw meat" is 膾(회), which is made up of the characters 月(육) and 會(회). 月(육) means "meat," and 會(회) means "meeting." The Chinese character for "meat" is 肉(육), but it is usually written as 月 when combined with other characters. Notice that the "meat," 月(육), and the "moon," 月(월), look the same, which can be confusing. However, when you see the 月 character, you can usually assume it means "meat," since the "meat" 月 is combined with other Chinese characters about 9 times more often than the "moon" 月. At any rate, the character for "sliced raw meat" is "a meeting of meat," not "a meeting under the moon."

膾(회) refers to both "sliced raw beef" and "sliced raw fish." If you want to distinguish between the two, you must say 肉膾(육회) for "sliced raw beef" and 生鮮膾(생선회) for "sliced raw fish."

My question is why isn't 鱠(회) used for "sliced raw fish" instead of 膾(회)? 鱠(회) is made up of the character 魚(어), which means fish. Wouldn't that make it a more appropriate composite character for "sliced raw fish"?

When one wants to refer to "sliced raw meat and fish" in general way, than 膾 is fine, but when one wants to distinguish between the two, then one should distinguish between the characters. Use 膾 in 肉膾(육회), but 鱠 should be used in 生鮮膾(생선회), not 膾.