PPT Slide
Euteleosts have externally symmetrical caudal fins, and the internal skeletal structure is nearly symmetrical. These fishes are able to hover in the water column and fine tune their position with coordinated movements of the caudal and paired fins. Note that this embiotocid (surf perch) from California is swaying with the water movement.
Also note the role of the uroneurals in stiffening the dorsal caudal lobe.