| Named By: | Deecke in 1911 |
| Time Period: | Early Triassic-Middle Triassic |
| Location: | Across Europe, Asia North America, North Africa and Madagascar, potentially worldwide |
| Size: | About 15 centimetres long, some variation between species |
| Diet: | Carnivore |
| Fossil(s): | Multiple individuals usually preserved flat upon stone slabs |
| Classification: | | Chordata | Actinopterygii | Perleidiformes | Perleididae | |
| Also known as: | | Dimorpholepis | Semionotus altolepis | |
Perleidus is an extinct genus of ray-finned fish from the Triassic period. Fossils have been found worldwide.
Perleidus was a freshwater predatory fish, about 15 centimetres (5.9 in) in length. Its jaws hung vertically under the braincase, allowing them to open wide, a feature it shared with the earlier palaeonisciform fish, from which it may have been descended. Unlike those earlier fish, however, Perleidus and its relatives had highly flexible dorsal and anal fins, with a reduced number of fin rays. This would have made the fish more agile in the water.