Put a North American madtom (Noturus) and an Asian amblycipitid side by side and you will see great similarities. After all, both are catfishes inhabiting riffles in the temperate north (although there are amblycipitids in tropical hillstreams, the bulk of the diversity is to be found northwards in colder climes), and both live out a loach-like existence among crevices.
The family Amblycipitidae is small, with only three genera and 26 species. Amblyceps (11 species) is the only genus found in the tropics, being known from Pakistan across the sub Himalayan region to the Indochinese and the Malay peninsulas. The other two genera, Liobagrus (13 species) and Xiurenbagrus (2 species), are found only in East Asia (China, Korea and Japan), reaching their southern limit in northern Vietnam. As for telling the three genera apart, Amblyceps can be distinguished from Liobagrus and Xiurenbagrus in having double folds on the upper and lower lips and uniformly colored fins, while Liobagrus has a single fold on the lips and fins with pale margins.Xiurenbagrus can be distinguished from Amblyceps and Liobagrus in having two patches of teeth (vs. one patch) in the upper jaw.
Amblycipitids are typically denizens of hillstreams and larger rivers that flow through hilly areas. A typical habitat would consist of a moderately fast flowing (but seldom torrential) stream with a sandy bottom interspersed with rocks. Amblycipitids are usually found hiding among the crevices under the rocks during the day, moving sinuously among the cracks at night when they come out to feed.
The similarity between madtoms and amblycipitids does not end with their general appearance. Some amblycipitids even exhibit the same form of sexual dimorphism as one would see in ictalurids. Nuptial males of Liobagrus have expanded cheek muscles as in those of Noturus, making their heads look remarkably similar to each other.
Considerable research on the biology of Amblyceps has been conducted, particularly in India (where it is a relatively common fish, at least in the sub Himalayan region and Gangetic plains). The streams and smaller rivers where Indian Amblyceps species live regularly become reduced to isolated pools, and these fish have evolved adaptations which enable them to switch from a hillstream type habitat (where dissolved oxygen is high) to a pool type habitat (where dissolved oxygen is considerably lower). This adaptation consists of air breathing organ, which is made up of the vascularized epithelium of the suprabranchial, bulla and opercular chambers (the region inside the cheeks and around the gills). When in water, the fish breathe spasmodically, taking several quick gulps before remaining quiescent (this may be the usual method by which sisoroid catfishes breathe, as an identical mode of breathing has been observed in akysids and sisorids). At intervals, the fish have been observed to rise to the surface for gulps of air, and is even said to float upside down motionless occasionally (this happens when the ingested air enters the stomach), although the ignificance of this behavior is not clear. Apparently, this air breathing adaptation is known only in Amblyceps mangois and A. laticeps, as field observations of a third Indian species, A. apangi, show that they are very sensitive to low dissolved oxygen.
How do amblycipitids rate as aquarium fish? Very well, if you are into catfishes and understand that keeping them involves not being able to see them most of the time. Amblycipitids are peaceful fish that can be kept in small groups (although conspecifics reportedly fight, I have not encountered this behavior; perhaps ample room is the key) and are ideal denizens for an Asian cool water biotope setup. Best of all, they are not too particular about food, and will take most aquarium foods. Amblyceps mangois breed at the onset of the monsoons (June-July),and this may be useful information in attempting to breed this species.
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