Kingdom:Animalia
Phylum:Chordat
Class:Actinopterygii
Order:Perciformes
Family:Scombridae
Genus:Katsuwonus
Species:K. pelamis

The skipjack tuna, Katsuwonus pelamis, is a medium-sized perciform fish in the tuna family, Scombridae. It is otherwise known as the aku, arctic bonito, mushmouth, oceanic bonito, striped tuna, or victor fish. It grows up to 1 m (3.3 feet) in length.

It is a streamlined, fast-swimming pelagic fish, common in tropical waters throughout the world, where it inhabits surface waters in large shoals (up to 50,000 fish), feeding on fish, crustaceans, cephalopods and mollusks. It is an important prey species for large pelagic fishes and sharks.

It is an important commercial and game fish, usually caught using purse seine nets, and is sold fresh, frozen, canned, dried, salted, and smoked.