FRESH-WATER FISHES OF SIAM, OR THAILAND 33 



The present author has observed the flanges in certain Indian fishes. 

 Dr. Hora, the keenest student of Indian fishes, states that he has 

 formed no opinion in regard to these structures. 



Mention has been made of the practice of oral incubation in the 

 three genera of Siamese catfishes of the family Tachysuridae. Asso- 

 ciated with this habit is the existence of secondary sexual characters 

 in both sexes, consisting in the male of a longer head, larger oral cavity, 

 more posterior insertion of pectoral and ventral fins, and smaller 

 ventral fins, and the development in the female on the inner ventral 

 rays of peculiar pads whose shape varies with the species. A conse- 

 quence of oral incubation is that the male, having taken in a batch 

 of eggs, is prevented from feeding until hatching ensues and the 

 young leave his mouth after the absorption of the yolk-sac. Sim- 

 ilarly, in the female feeding becomes more and more difficult with 

 the gi'owth of the enormous eggs, and a point is reached when the 

 digestive organs are so compressed that they become nonfunctional, 

 and no food can enter the stomach or intestines. It naturally follows 

 that by the time the eggs are laid and the protracted hatching period is 

 over both parents become much emaciated. This subject is discussed 

 at some length in the systematic treatment of the Tachysuridae. 



INTRODUCED SPECIES 



A few species of cyprinoid fishes have been introduced into Thai- 

 land, mostly by Chinese and from China. These have been brought 

 in the young stages in vessels from Hong Kong and Swatow and have 

 been grown in artificial ponds or in f enced-off sections of canals, mostly 

 in Bangkok. Some of the fishes have from time to time escaped from 

 captivity and gained access to open waters, and in the future they will 

 doubtless have to be reckoned with as a regular element of the local 

 fauna. Such escaped fishes have been taken in the Menam Chao Phya 

 as far north as Paknampo, and there is nothing to prevent their ulti- 

 mate dispersal all over Central Thailand. 



The business of transplanting food fishes from China to Thailand 

 has depended on the ease with which certain kinds may be transported, 

 their ready susceptibility to growth in ponds, and the ready sale 

 among the large Chinese population of particular fishes with which 

 the Chinese were familiar at home. 



Following is a list of exotic cyprinoid fishes that have been taken 

 to Thailand and successfully acclimatized in ponds; introduction of 

 various other species may be expected from time to time : 



Cyprimis carpio Linnaeus. Common carp. 

 Carassius auratus (Linnaeus). Goldfish. 

 Aristichthys nobilis (Ricliardson). 

 Cirrhinus moUtorella (Cuvier and Valenciennes). 



