He nōpili ka iʻa, pili paʻa ke aloha.

“The nōpili is the fish; love clings fast.”

Said of the freshwater goby (‘o‘opu) of the nōpili variety, known to clime waterfalls by clinging fast to the wet stones. It was used by kāhuna in hana aloha sorcery.

Source: ʻŌlelo Noʻeau, by Mary Kawena Pukui

Hanakapi‘ai Falls is seen here on this photo taken mid-July. The ʻoʻopu nōpili is an endemic type of freshwater goby found in all main Hawaiian Islands, including at Hanakapia‘i Stream on Kaua‘i. A 1980s study conducted by the U.S Fish and Wildlife, in collaboration with the University of Hawai‘i and the DLNR Department of Aquatic Resources found out the ʻoʻopu nōpili utilizes faster flowing water than the indigenous ʻoʻopu nakea and the endemic ʻoʻopu ʻalamoʻo, two other types of goby found at Hanakapiʻai Stream.