What is Plectranthias kojii?

Plectranthias kojii is a species of fish belonging to the family Serranidae, commonly known as the “Koji’s perchlet.”

It was first described in 2008 from specimens collected in the Ryukyu Islands, Japan.

The fish has a distinctive coloration, with a bright red head, orange-yellow body, and blue stripes on its fins. It inhabits rocky reefs and coral formations at depths ranging from 65 to 100 meters.

Like other members of the genus Plectranthias, P. kojii is a small, carnivorous fish that preys on small crustaceans and other small fish.

It is a popular species in the aquarium trade, although it is relatively rare and expensive due to its limited distribution and difficulty in capturing and transporting.

Despite its popularity, little is known about its biology and ecology in the wild, and further research is needed to better understand its conservation status and the potential impact of trade on its populations.


The marbled perchlet is a small, colorful fish that is native to the waters of the Indo-Pacific region.

It is highly prized by aquarium enthusiasts for its stunning appearance and peaceful demeanor, making it a popular addition to community tanks.

The new species was discovered by a team of researchers during a survey of the marine life in the waters off the coast of Indonesia.

The fish is characterized by its unique marbled pattern, which is a combination of bright orange, yellow, and black markings that create a stunning visual effect.

It is believed that this new species of marbled perchlet may have only recently evolved, making it an exciting find for scientists studying the evolution of fish species in this region.


What’s different about this Attractive New Species of Marbled Perchlet?

The marbled perchlet is different due to its unique coloration and pattern.

It has a marbled pattern of yellow, orange, and brown on its body, with a bright blue stripe running along its head and back.

This makes it stand out from other species of perchlet in its habitat.

This species has been found to have a different genetic makeup than other perchlet species in the area, indicating that it may have diverged from other species in the distant past.

Its discovery highlights the importance of continued exploration and study of the world’s oceans in order to uncover new and fascinating species.


Plectranthias kojii is the newest species of perchlet from the cradle of biodiversity for this genus which appears to be the northwest Pacific Ocean. This Japanese perchlet was first recognized as being something new and different by the staff at the Blue Harbor Aquarium Factory in Japan who provided the type specimen used in the description of Plectranthias kojii.

Koji’s perchlet was collected at the bone crushing depth of 150 meters, or just shy of 500 feet deep off Hamahiga-jima Island, near Okinawa-jima Island, Japan and is most closely related to one of the other newest species of perchlet, Plectranthias ryukyuensis which is also from Japan. Plectranthias kojii is a mostly brown perchlet species with a marbled or peppered appearance consisting of irregular white and brown blotches throughout its body, with an angular dark brown bar streaking across the body underneath the dorsal fin that itself is underscored by five circular white patches of color.

The holotype specimen of Plectranthias kojii clocked in at 49 mm or just about two inches long making it about average in size compared to other species in this genus of mostly small deepwater fish. With the description of Plectranthias kojii the genus now contains 65 officially recognized species with nearly a third of those, 18 total, known from Japan alone. Koji’s Perchlet is named after both Koji Abe (who collected the fish) and our friend Koji Wada (who donated the specimen) and was described by Koeda et. al in the latest edition of Ichthyological Research.

Published at Thu, 28 Oct 2021 11:29:10 -0400

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