Actinopterygii or the ray finned bony fishes are the dominant class of not only fish, but of vertebrates with an estimated 30000 species. Since you didn't ask specifically I've given you a pretty general answer. Actinopterygii contain many orders and classes of fish.
Domain Eukarya Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrae Class: Actinopterygii Genus Perca Species Perca flavescens
Ray-finned fishes (Actinopterygii)
Reedfishes, sturgeons, herrings, cods, flatfishes etc are members of actinopterygii.
Kingdom: Animalia Phylum: Cordata Class: Actinopterygii Order: Scorpaenidae Subfamily: Pteroinae Genus: Pterois Species: volitans
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Beloniformes Family: Chanidae Genus: Chanos Species: Chanos chanos
Actinopterygii
To avoid you having to ask for more. :- The Class for Tuna is "Actinopterygii". Its Order is "Perciformes" the Family is "Scombridae". and the Species is "Thunus".
Scientific classification Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Cypriniformes Family: Cyprinidae Genus: Cyprinus Species: C. carpio
actinopterygii
There are 30 species of seahorses, all in the genus Hippocampus Kingdom Animalia Phylum Chordata Class Actinopterygii Order Syngnathiformes Family Syngnathidae Genus Hippocampus
Most likely it is a misspelling of actinopterygii