TOKYO >> A mysterious fish that lives deep below the ocean’s surface has been popping up in the waters of Toyama Bay, causing marine experts to scratch their heads.

A deep-sea slender oarfish was caught in a fixed net .62 miles off Imizu Jan. 28 and delivered to the Uozu Aquarium in Uozu in the prefecture.

That makes three fish caught in Toyama Bay last month, as two slender oarfish were also found on Jan. 19 in waters off Imizu and Namerikawa.

Slender oarfish, characterized by long silvery-white bodies and red fins, live at a depth of 656 to 984 feet. The fish is called “ryugu no tsukai” in Japanese, meaning “messenger from the palace of the dragon king.”

The latest fish caught was nearly 13 feet long, the fourth longest to be found in Toyama Prefecture. According to the aquarium, 20 slender oarfish have been found in Toyama Bay since 2009. Four fish were found in 2015, the most in a single year.

“(Finding several in a row) is said to be the forerunner of an earthquake or to be influenced by ocean temperatures, but research is scarce and we don’t know the cause,” said Satoshi Kusama, 35, a caretaker at Uozu Aquarium.

According to the prefecture’s Fisheries Research Institute, the water temperature on the surface of Toyama Bay this month is several degrees higher than usual, while temperatures at the depth of the fishes’ habitat are slightly below average.

The fish’s carcass is in good condition and was exhibited last weekend at the aquarium.