Origin of the Japanese Name: Opsariichthys platypus (Oikawa)


“Oikawa (Opsariichthys platypus)” is a fish widely distributed throughout Japan. It inhabits most rivers and is a common species. However, in my opinion, among freshwater fish in Japan, its coolness ranks in the top 5. Around this time (July) during the spawning season, the males turn blue, and their anal fins become red and extend. It is quite beautiful.

The English name of this species is Pale Chub, which accurately reflects its appearance. It’s a fitting name.

Now, what does the Japanese name “Oikawa” mean? It means “chasing each other in the river.” During the spawning season, the males chase each other to claim their spawning grounds. This movement seems to be the origin of the name. This chasing behavior does indeed occur, but you have to observe the river closely to notice it. I am impressed by how keenly people observed things in the past. The fact that the name is not influenced by the fish’s appearance is quite stylish. The attitude of “we truly understand this fish and have named it appropriately” captivates me.

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