Both species are characterized by large size, cryptic coloration and prominent ear tufts. A closer inspection of the Brown Fish Owl will reveal specialized traits that set it apart from most other owls in its family. Fish owls of the genus Ketupa have no feathers on their lower legs and feet to get wet when they snatch prey from surface of the water. The soles of their feet have specialized spiny scales called spicules that enable them to grip slippery aquatic prey securely.
Most owls have a short comb-like fringe on the forward edge of their outer flight feathers.
This fringe is believed to reduce the sound created by flapping wings. Silent flight allows typical owls to approach their prey without being heard. Fish owls lack this fringe structure on their primaries. A silent approach may be less important to an owl hunting underwater prey. One of the most obvious characteristics of the owl family is the facial disc, a specialized arrangement of facial feathers under muscular control.