diving beetle; Japanese predacious diving beetle
Refers to diving beetles in general, and specifically to Cybister japonicus, a large species found in Japan. Often kept as a pet by children.
When I was a child, I caught diving beetles in the rice paddies.
Diving beetles eat small fish underwater.
Japanese crucian carp; white crucian carp
Usually written in katakana; the kanji form 源五郎 is rare.
Kanji spelling; rarely used.
Hiragana spelling, also common.
The name ゲンゴロウ is said to come from the personal name 源五郎 (Gengorō), but the exact origin is uncertain.