Tke Mexican Swordtail 



GEORGE S. MYERS 



Typical male of Xiphophorus helleri ( upper ) and two variants 



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The Mexican Swordtail, Xiphophorus 

 helleri, was described and named by the 

 naturalist Heckel in 1848. It occurs ex- 

 tensively from Southern Mexico and 

 Central America to Venezuela in com- 

 pany with Platvpoecilia, Mollienisia, 

 Poecilia and other members of the group 

 of live-bearing tooth-carps familiar to 

 aquarists. It was first secured by German 

 aquarists in 1909 and was brought to this 

 country about a year later. It soon be- 

 came popular and is now the most easily 

 procured exotic aquarium fish. Beautiful 

 coloration and interesting breeding habits 

 made friends for it everywhere. 



The body, in the male, is an intense 

 silvery-blue which in some specimens 

 shows a decided greenish tinge. Along 

 the side, ending at the tail-fin, is a red or 

 reddish line. The dorsal fin is large, re- 

 minding one of Mollienisia, and marked 

 with dots of claret. The gill-covers are 

 bright silver-blue. The sword, a pro- 

 longation of the lower rays of the tail, 

 is in some individuals a metallic peacock 

 green, and in others yellow or bright 

 orange. In all cases it is outlined with 

 black. Fish bred from stock brought 

 from Venezuela have in addition to the 

 usual red lateral stripe, a wide reddish- 



