342 THE AQUARIUM 



Alfaro cultratum is one of the most interesting fishes of 

 the live-bearing group. It is known only from the Carib- 

 bean slope of Central America, where it inhabits swift, 

 stony-bottomed brooks. Well-grown specimens reach three 

 inches in length and are olive in general color, with patches 

 of brilliant blue and green on the body, and yellowish tail. 

 The anal fin of the male is very far advanced, and in both 

 sexes the space along the ventral line between this fin and 

 the tail is occupied by a double row of scales which forms 

 a curious, keel-like structure. The first specimens to reach 

 this country were collected in Costa Rica by the writer, and 

 have proved both hardy and prolific in captivity, taking 

 kindly to the ordinary diet of aquarium fishes. 



Some of the smallest known fishes belong to the genus 

 Heterandria, of which a Mexican form, H. formosa, is the 

 only species known among American fish culturists. Large 

 females reach an inch and sometimes slightly more, but 

 the males are never more than three-quarters of an inch in 

 length and mature at much smaller size. It is an attractive 

 fish, olive brown in color, with dark lateral stripe and dorsal 

 spot. It is very hardy in the aquarium, breeding freely and 

 sustaining itself with algae and prepared food. 



Certain small members of the Cyprinidce, or carp group, 

 are mentioned here, instead of with their allies, because the 

 nature of their habitats necessitates their treatment being 

 that of other tropical forms. 



The genus Barbus contains a number of European and 

 Asiatic species which grow to a very large size, but there 

 are many smaller ones which are in favor with aquarists. 

 They are harmless, fairly active fishes, rather broad in pro- 

 portion to their length and often strikingly marked, al- 

 though they do not present the brilliant colors of some other 

 groups. B. maculatus, B. ticto and B. vittaius are some of 

 the more familiar species. They are easily kept at warm 



