Chaca Gray, 1831
Carl J. Ferraris, Jr., 2007, Zootaxa 1418: 1-628 
Chaca is the only genus in the catfish family Chacidae. These fish are commonly known as squarehead catfishes, frogmouth catfishes, or angler catfishes. These unusual fish have a sedentary lifestyle and spend much of their time immobile.
The name Chaca is derived from the fact that when removed from the water, they will rapidly repeat the sound "chaca". Only C. chaca makes these sounds; the other species do not.
Chaca species are found in freshwater from eastern India to Borneo. C. chaca is found in the Ganges-Brahmaputra River system of India and the Ayeyarwady River of Myanmar. C. bankanensis originates from the Sundaland region. C. burmensis is found in the Sittang River in Myanmar and possibly the Ayeyarwady drainage.
C. chaca is found in rivers, canals, and ponds of grassland, scrubland, deciduous forest, and rainforest habitats. On the other hand, C. bankanensis is only found in the rainforest, where it inhabits peat.
Appearance and anatomy
Chaca catfish have an elongated, broad, and flattened head. The mouth is terminal and very wide. There are three or four pairs of barbels, though if the nasal barbels are present they are minute. These fish grow to a length of about 20 centimetres (7.9 in).
The dorsal fin is short and possesses strong, serrated, fin spines, which are strong enough to inflict wounds.
These fish live in soft substrates where they will bury themselves as camouflage, both for protection and to feed. These fish are ambush predators. They feed on prey such as small fish, including cyprinids and pupfishes. They will lie in wait, well camouflaged, in preparation for prey to swim by. Sometimes, they use their maxillary barbels to lure prey fish closer to its mouth, similar to a worm jerking in the water, although this behavior is contested by some aquarists who do not observe this behavior. When the catfish is ready to strike, the Chaca will open its large mouth rapidly, creating a vacuum that pulls in water and its prey, which may be up to half the fish's own length. These fish are also able to use this large mouth as a means of propulsion; when frightened, they will gulp a large amount of water and expel it through their gills.
In the aquarium
Chaca species are occasionally available as aquarium fish. These fish are nocturnal and are usually inactive.  A bizarre phenomenon is shown in that Chaca appear to lower the pH of the water, and so maintenance of water chemistry is necessary. These fish have been bred in captivity.
1. ^ "Chacidae". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=164133. Retrieved May 8, 2007.
Source: Wikipedia, Wikispecies: All text is available under the terms of the GNU Free Documentation License