No.50 Ayu Fish

Ayu Fish is a freshwater fish that inhabits rivers throughout Japan. It is known as an “annual fish” that spends its entire life cycle in one year, swimming upstream in rivers from spring to summer and then returning downstream in autumn to spawn.
They typically grow to a length of 15–25 cm and are characterized by their silvery bodies and yellow-greenish backs. They feed on algae attached to riverbed rocks, so they have developed hard teeth around their mouths. They are also known for their strong territorial instincts.

This sample was requested by NHK Enterprises, Inc. and CT scans were conducted as a project for NHK E-television's “Gyogyotto Sakana★Star”.
Gyogyotto Sakana★Star" program HP: https://www.nhk.jp/p/ts/P58QMGP4K1/

CT scans allowed us to examine the details of the pectoral, dorsal, and caudal fins, revealing that the caudal fin bones were shaped to efficiently transmit propulsive force. The bones around the gills and the arrangement of the gill arches, which serve as supports, were also clearly visible, revealing a sophisticated mechanism that allows the fish to breathe and feed at the same time.