Vol. XXIV, pp. 91-96 May 15, 1911 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



BREEDING HABITS OF THE VIVIPAROUS FISHES 

 GAMBUSIA HOLBROOKII AND HETERANDRIA 



FORMOSA. 



BY WILLIAM P. SEAL. 



The two species under observation belong to a well-defined 

 group of small fishes the members of which are variously known 

 as ' ' Top Minnows, " " Mud Minnows, " " Pike Minnows, " " Kil- 

 lifishes," etc. The generic name Gambusia was suggested to 

 the late Professor Poey by the common name in use in Cuba, 

 Gambusino, meaning small and of no importance. The mem- 

 bers of fhis genus are larger than those of Heterandria and have 

 a more northerly range; the females, however, though usually 

 twice as large as the males, rarely reach a length of two and one 

 half inches. Until the discovery by Dr. Smith that the little 

 fish named by him Mistichthys reached the adult stage at less 

 than an inch in length Heterandria was about the smallest 

 known vertebrate. According to Garman the range of Gam- 

 busia holbrookii is from Virginia to Alabama and is represented 

 in the tributaries of the Mississippi and westward to Mexico by 

 its close ally G. patruelis. Heterandria fomiosa is abundant in 

 swamps and ditches coastwise from the Carolinas to Florida. 

 It- rarely exceeds an inch in length. 



Gambusia was introduced into New Jersey in 1905 and from 

 observations made by me of both it and Heterandria since 1906 

 the habits of the two are, so far as discernible, exactly similar. 

 They are the most northerly representatives of the viviparous 

 genera of the family Poeciliidae. They are easily kept in small 

 glass jars where they breed readily, eating anything that a gold- 

 fish will eat, either vegetable or animal, and as insect destroyers 

 have no superiors. 



22— Proc. Biol. Soc. Wash., Vol. XXIV, 1911. (91) 



