Rainbow trout, a trout and species which is native to cold tributaries, belongs to the Kingdom Animalia, Phylum Chordata and Class Actinopterygii, which include ray-finned fishes.
The rainbow trout (Oncorhynchus mykiss) is a trout and species of salmonid native to cold-water tributaries of the Pacific Ocean in Asia and North America. Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Actinopterygii (/ktnptrdia/) (New Latin, actino- ("having rays") + Ancient Greek  (pterux, "wing, fins")), members of which are known as ray-finned fishes, is a clade (traditionally class or subclass) of the bony fishes. 
