FRESH-WATER FISHES OF SIAM, OR THAILAND 29 



Indo- Australian Archipelago. There is no brook, rivulet, river, canal, 

 or lake in which the family is not represented ; and a net or trap may 

 hardly be drawn anywhere at any time without yielding one or more 

 species. Some species occur in incredible numbers in certain places 

 at certain times, others may be found only singly, and several strik- 

 ing species are as yet known from only single specimens. The whole 

 gamut of size among cyprinoid fishes is run by the family in Thai- 

 land from the most diminutive only 2 cm. long to the colossal Catlo- 

 carpio siam-ensis, peculiar to Thailand and French Indo-China, which 

 attains a length of 3 meters and may be the largest member of the 

 family. From the viewpoint of the domestic food supply, the family 

 is of incalculable importance. 



A very prominent element in the fresh-water fish fauna is the 

 loaches (Cobitidae). Herein recognized are 8 genera and 38 species. 

 Several genera are peculiar to Thailand, and a number of species 

 belonging to genera widely distributed in southern Asia and the Indo- 

 Australian Archipelago are known only from this country. These 

 fishes are characteristic of mountain streams, where they bury them- 

 selves in sand and gravel. Some, however, lacking the burying habit, 

 are found in large, muddy rivers and even in lakes. 



A very conspicuous feature of the fauna is the abundance of cat- 

 fishes (Nematognathi) as regards both species and individuals. The 

 local representatives herein considered fall into 10 families, 34 genera, 

 and 100 species. Some of them are found only in mountain brooks, 

 some only in the large rivers, and some throughout certain river basins 

 from their headwaters to their brackish-water mouths. Two panga- 

 siids are among the largest catfishes in the world; one species, 

 Amhlyceps mangois, is among the smallest. In one family (Sisoridae) 

 some genera have a thoracic adliesive apparatus enabling the fish to 

 cling to stones in swift current ; other genera have the whole underside 

 of the head and the pectoral and ventral fins modified so as to serve 

 as an adhesive organ. All the members of one family (Clariidae) 

 have an accessory breathing organ, occupying a cavity on each side 

 of the head above the gills. In one family (Heteropneustidae) there 

 is a supplementary respiratory apparatus consisting of two long hol- 

 low cylinders extending among the muscles of the back. In at least 

 three genera of one family (Tachysuridae) comprising many species 

 the eggs are incubated in the mouth of the male. 



The tendency of certain kinds of flatfishes in various parts of the 

 world to establish themselves in fresh water is manifested in a striking 

 manner in Thailand where representatives of three soleid genera are 

 found far inland in places where the water is always fresh. Some of 

 these fishes are met with several hundred miles from the sea above 

 rapids that are believed to be nonnegotiable by such fishes. No obser- 

 vations have been made on the spawning habits, eggs, hatching, and 



