| Scientific name | Plotosus japonicus |
| English name | Japanese eel catfish |
| Japanese name | 権瑞 |
| Class | Osteichthyes |
| Order | Siluriformes |
| Family | Plotosidae |
| Genus | Plotosus |
| Species | japonicus |
| Subspecies | --- |
| Full length | ~20cm. |
| Distribution | Honshu and southwards. |
At first glance, it looks like a tadpole. It has a dark brown body with yellow vertical lines. There are 4 to 8 beards around the mouth. It has poisonous pectoral and dorsal fins that cause severe pain when stung.
Juveniles and similar-sized gonzoi form spherical shoals. This is called "Gonzui ball". I often see gonzui in gonzui ball state.
They live in groups on rocky reefs and tidal pools. It eats organisms near the seabed. Juvenile fish are often seen in the daytime, but adults have the impression that they often live in the shade of rocks.
When you're in Arasaki, you'll often see Gonzui balls even if you're not looking for them. Juveniles vary in size, but groups of small individuals sometimes swim in tidal pools.
Juvenile snails were also spotted here and there, but adult fish were swarming in the darkness under the pier.
Introducing a picture of Japanese eel catfish.