Japanese crucian carp (cultured variety)
Specifically refers to the artificially cultured form of the Japanese crucian carp (ゲンゴロウブナ), bred for fishing and often called 'hera-buna'.
See also: ゲンゴロウブナ
Hera-buna fishing is one of Japan's traditional fishing styles.
There are many large hera-buna in this pond.
Katakana spelling is common for this fish name; usually written in kana.
Kanji form is rare and mainly encountered in specialized or historical contexts.
The name likely derives from the shape of the fish's body resembling a spatula (箆, へら) combined with 鮒 (ふな, crucian carp). The exact origin is uncertain.