Nandidae
From The Aquarium Wiki
Nandidae, or Asian Leaffish, belong to the order Perciformes. There are 4 genera in this family with 9 known species. They usually have small heads, cryptical colors and very large protractile mouths. Those features, along with their peculiar movements help them to catch fairly large prey compared to their bodies, including small fish, aquatic insects and other invertebrates.