FRESH-WATER FISHES OF SlAM, OR THAILAND 289 



BOTIA HYMENOPHYSA (Bleeker) 



Colitis hytnenophysa Bleekeb, 1852 (67), p. 602 (Palembang, Sumatra). 



Botiu hymenophysa Bleeker, 1865 (347), p. 35 (Siam) ; 1865 (356), p. 175 

 (Siam).— GuNTHEK, 1868, vol. 7, p. 368 (Siam).— Sauvagb. 1881, p. 164 

 (Siam) ; 18S3b, p. 154 (Menam Chao Pliya). — Webeb aud de Beaufort, 1916, 

 vol. 3, p. 24 (Siam).— HoRA, 1923b, p. 148 (Nontaburi).— Fowler, 1934a, 

 p. 101, figs. 51, 52 (Cliiengmai) ; 1935a, p. 106 (Srisawat, Khao Nam Poo) ; 

 1937, p. 154, figs. 64-69 (Bangkok, Tachin, Kemarat). 



Botia hynieopliysa Smith, 1930, p. 55 (Siam). 



This is a very common fish in parts of Central and Northern Thai- 

 land, in the basin of the Menam Chao Phya. During November of 

 several j'ears Klong Borapet, the principal outlet of Bung Borapet, 

 was found to be literally teeming with fish 6 to 8 cm. long on their 

 way from the lake to the Menam Nan. In the basin of the Mekong, 

 the fish has been taken at Kemarat in the Mekong, and in the Menam 

 Chi at Udon, Eastern Thailand. 



The maximum size of the fish in Thailand is about 22 cm., but the 

 usual run of adult fish is 12 to 15 cm. 



This is a strikingly beautiful fish in life, undergoing considerable 

 change in pattern of coloration with age. Two adults, 12.8 and 13.1 

 cm. long, obtained in the Menam Chao Phya near Bangkok Novem- 

 ber 30, 1930, had the following coloration when taken from the water : 

 Back and sides yellow, with 11 slightly oblique blue cross bands wider 

 than the interspaces, the dorsal part of the last cross band much 

 darker and constituting a blue-black spot, top of head blue ; belly and 

 underside of head pale yellow; dorsal fin yellowish orange, with 4 

 blue cross lines ; caudal fin yellowish green, with 4 narrow blue cross 

 lines on basal half ; anal, ventral, and pectoral fins bright yellow. 



Two specimens in the British Museum from "Pachebon" on the 

 upper Pasak were collected by the celebrated traveler and explorer 

 Mouhot. Regarding these specimens Giinther said (1868, vol. 7, 

 p. 368), "A variety * * * having only eleven cross bands, which 

 do not appear to be edged with blue, and the last cross band termi- 

 nates in a black spot superiorly on the root of the caudal fin." This 

 is a common color phase of the species, and such specimens have been 

 met with at Bung Borapet, Bangkok, and other places. 



Fowler (1934a) published two figures of B. hymenophysa from 

 Chiengmai to show variations in color, but the specimens on which the 

 drawings were based are obviously not conspecific, one (fig. 51) having 

 12 branched rays in the dorsal fin, the other (fig. 52) having 7 such 

 rays. Fowler later (1937) identified the latter figure with his 

 B. lucas-hahi, from the Tachin. 



Throughout its range the fish is known as pla mu (hog fish) , a name 

 borne also by other species of this genus. A distinguishing name used 

 in some sections is pla 7nu hang lai (striped-side hog fish). 



