FRESH-WATER FISHES OF SIAM, OR THAILAND 461 



With all the solicitude shown by a male for his progeny, it may be noted that 

 he cannot distinguish his own young from those of another parent introduced 

 into his aquarium. Foster offspring receive the same care as his own. 



Another aspect of the interesting behavior of Betta is shown when a male 

 parent is taken away from his nest and returned after a few days ; he promptly 

 devours his young. 



The fighting fish is a confirmed carnivore. This would be indicated by its dental 

 equipment and short intestine even if not shown by direct observation on wild 

 and domesticated fish. 



In a wild state, the fish renders a useful service to mankind and to land animals 

 generally by its destruction of mosquito larvae. The fish inhabits the same kinds 

 of weedy waters in which the eggs of various mosquitoes are laid and hatched, 

 and mosquito larvae are the favorite, often the exclusive, food throughout the 

 year. As the fish's appetite is keen, its digestion rapid, and its feeding activities 

 more or less continuous during daylight, the daily consumption of potential blood- 

 sucking pests is large. Based on the observed requirements and the actual con- 

 sumption of mosquito larvae by fighting fish in small aquaria, I would not hesitate 

 to estimate an annual intake of 10,000 to 15,000 larvae per adult wild fish under 

 normal conditions. 



When the young fishes first begin to feed their mouths are too small to admit 

 mosquito larvae, and during a period of 10 to 12 days following the absorption of 

 the yolk sac tliey subsist chiefly on minute crustaceans, which swarm in the local 

 waters. 



The preference is for living, moving food. Given the choice of both active and 

 dead larvae, the fishes may entirely reject the latter until driven by extreme 

 hunger. Under the stress of necessity they will take selected nonliving food and 

 thrive on it. A lot of fishes that I took from Bangkok to San Francisco were, after 

 the first few days of the voyage, fed successfully on minute scrapings of raw fish 

 provided by the ships' stewards. 



In Siam, mosquito larvae are regarded as essential for the proper nourish- 

 ment of fish under domestication. For supplying the daily needs of my fighting 

 fish in Bangkok, two coolies spent much of their time in locating breeding places 

 of mosquitoes, collecting the larvae with flne-mesli nets, separating the larvae from 

 plant and animal debris, and feeding the clean larvae to the fish at regular times 

 and in quantities based on the reactions of the fish. The wrigglers, held in a 

 coffee cup or rice bowl, were administered with a spoon. 



In the capital of Siam where there are some thousands of amateur fighting-fish 

 fanciers and many professional breeders and dealers, there is a large and steady 

 demand for mosquito larvae. To meet this demand, which becomes acute during 

 the dry season, there has sprung up the strange business of breeding mosquitoes 

 and selling their larvae to owners of fightingfish ; and a number of people thus 

 gain a livelihood. 



The Thai name is pla hat (biting fish) . 



Genus TRICHOGASTER Bloch 



Trichogaster Bloch, in Schneider, Systema ichthyologiae, p. 164, 1801. (Type, 

 Latrus trichoptcrus Pallas.) 



As pointed out by Myers (1923, p. Ill) the fishes usually called 

 Trichopodus (Lacepede, 1802) should bear the name Trichogaster^ first 

 used by Bloch (1801), Trichopodus being a synonym. The type spe- 



