n"rte Mexican Swordtails 



WALTER LANNOY BRIND, F. Z. S. 

 WATER COLOR BY A. DESCHERMEIER 



Mexican Swordtail XiphopKorus helleri Courtesj) of the Chicago Aquarium Societp 



Probably no "tropical fish," as we use 

 the term, is better known to all of us 

 than the Mexican Swordtail, otherwise 

 Xip hop horns helleri. Under this name 

 the fish with the markings and coloration 

 of the illustration above was introduced 

 into Germany in the spring of 1909 — a 

 single specimen. A little later more were 

 received and bred in large quantities, the 

 price of a pair dropping rapidly from 

 $12.50 to $1.50, a price approximately its 

 present value in the United States today. 

 This fish made a bigger "hit" in Germany 

 than any other aquarium fish before or 

 since. Its beautiful colors and the ease 

 with which it could be propagated by the 

 veriest amateur attracted attention at 

 once. During my stay in Berlin in 1910 

 I secured a pair, paying, if I remember 

 right, about six marks. At that time no 

 other species or variety of swordtail was 

 known in Germany. 



Heckel described Xiphophorus helleri, 

 but, according to Professor Regan, of the 

 British Museum, to whom the Germans 

 formerly sent all new fishes for identifi- 

 cation, the fish introduced was not X. 

 hellen, but X. Guentheri. The differ- 



ence between these two varieties lies in 

 such fine points as the number of scales 

 in the lateral line, rays of the fins, and 

 so on. These distinctions, while neces- 

 sary to the work of the systematic ichthy- 

 ologist, need not concern us aquarists ; 

 we are more interested in studying the 

 habits of the fishes. The late Seth Eu- 

 gene Meek, of the Field Museum, Chi- 

 cago, who had abundant opportunities to 

 study and observe this fish in its native 

 Mexico, considered helleri and guentheri 

 as merely varieties, and not distinct spe- 

 cies as we accept the term. I hold this 

 view — local climatic, geological and wa- 

 ter conditions influence to a pronounced 

 degree the coloration, markings and other 

 characteristics of many fishes. The 

 American brook trout taken from a num- 

 ber of streams will differ considerably, 

 but no sane scientist considers the varia- 

 tions sufficient to warrant making new 

 species. The student is already bothered 

 sufficiently with names better left uncon- 

 ferred. Anyway, the old name of helleri 

 will probably stand, having been the first 

 adopted, as far as we aquarists are con- 

 cerned. 



