Finneon is a small fishlike Pokémon with an ellipsoid body. The bottom half of its body is light-blue while the top half is black. A pink stripe runs across either side of Finneon's horizontal length. It has small blue pectoral fins, two black oval-shaped dorsal fins, and pink eyes. Finneon's most notable feature is the pair of caudal fins that resemble a pair of blue butterfly wings with pink spots. The bottom lobes of a female Finneon's tail fin are bigger than a male's. Finneon's pink stripes and spots can absorb sunlight, which allows those areas to shine vividly at night. Finneon shines itself as a form of camouflage, as well as to attract prey.
Because of its wing-like fins and beautiful appearance, Finneon is known as "The Beautifly of the Sea" and "finery fish". It lives in bodies of water, and it travels in schools, sometimes with Lumineon. Finneon is popular with divers; as a result, it is found living near resorts that feed them. It swims near the surface during the day to absorb sunlight, then dives into deeper waters at night. It is able to jump high and breach the water's surface with its tail fins, where it is then caught by its natural predator Wingull.
Finneon made its main series debut in Staging a Heroes' Welcome!, under the ownership of Zoey, who used it during the Performance Stage of the Wallace Cup. Finneon was revealed to have evolved into Lumineon by Last Call — First Round!.
Finneon debuted in The Rise of Darkrai.
A Finneon appeared in Giratina and the Sky Warrior.
In Hold the Phione!, multiple Finneon were living at Chocovine Town.
In Strategy Begins at Home!, Team Rocket was fishing for Goldeen in a lake where a Finneon lived.
In Going for the Gold!, multiple Finneon were living in the Ambrette Aquarium.
Multiple Finneon appeared in Alola to New Adventure!.
Multiple Finneon appeared in The Guardian's Challenge!.
Four Finneon appeared in Yo, Ho, Ho! Go, Popplio!, with one being wild and the other three appearing in a fantasy. Lana gave the wild one some food after capturing it by fishing. It was later captured by Team Rocket.
Multiple Finneon appeared in The Island Whisperer!.
Multiple Finneon appeared in Balloons, Brionne, and Belligerence!.
In Dewpider Ascending!, a Finneon checked out a Dewpider soon after it entered the ocean before swimming off.
In Don't Ignore the Small Stufful!, a Finneon was staying at Aether Paradise.
A Finneon appeared in Keeping Your Eyes on the Ball!.
Multiple Finneon appeared in Pikachu's Exciting Adventure!.
In The Sinnoh Iceberg Race!, a Trainer's Finneon competed in the Pokémon Iceberg Race.
Three Finneon appeared in Getting More Than You Battled For!.
||Finneon, the Wingfish Pokémon. Because of its twin-tail fins that flutter like wings when swimming, Finneon has been called "The Beautifly of the Sea."