aquatic JLitt 



99 



aquaria, having a temperature of 75 de- 

 grees Fahrenheit. Breeding is extremely 

 easy. It is merely necessary to place th^ 

 female, when she seems about to drop 

 the young, in a tank full of a dense 

 growth of plants. The species is, of 

 course, live-bearing, and when the young 

 have been expelled the female should be 

 removed at once, otherwise she will 

 promptly devour her offspring. Every 

 aquarist should have a few swordtails in 

 his tanks, if only one or two forms. 



Holbrook's Gambusia 



G. P. VON HARLEMAN 



In the opinion of the writer Gambusia 

 affinis var. holbrooki, a member of the 

 tooth carp family, is one of the most de- 

 sirable and interesting of our aquarium 

 fishes. Experienced fanciers have kept 

 and bred the species for years, but all 

 novices are not acquainted with it, and 

 for them this article is written. It in- 

 habits our Southern States, and particu- 

 larly the fresh waters of Louisiana and 

 Florida. 



A full-grown male measures one inch 

 long, rarely will it be one and one-half 

 inches. Average specimens are silvery 

 white, or yellowish white, with regular 

 black spots. Those with the silvery white 

 ground color are preferred, the blackest 

 specimens being held in the highest 

 esteem. All-black ones have been pro- 

 duced by selecting as breeders males on 

 which it was the dominant color. These 

 little jet black fellows, with glistening 

 white eye , are exceptionally handsome 

 fish. 



A casual observer would probably mis- 

 take the female of the species for an 

 entirely different fish, so different is she 

 from her mate in color, and so much 

 larger — one and one-half to two and one- 

 fourth inches in length. Her back is 

 gray-brown ; sides light olive, with a 



metallic lustre; dorsal and caudal fns 

 beautifully rounded and evenly marked 

 with small dark dots ; belly is white, with 

 a black spot on the sides. I don't agree 

 with those writers who consider this spot 

 an indication of pregnancy as far as this 

 species is concerned. I have had a fe- 

 male alone in a small tank for several 

 months, and at the end of the period the 

 spot was just as prominent, no young 

 having been expelled. 



The Holbrooki is a prolific fish, and 

 will expell a batch of youngsters at in- 

 tervals of four to six weeks during the 



Gambusia affinis holbrooki 



From "Domesticated Fish" by W. L. Brind 



spring and summer. From ten to thirty 

 will be born at a time, the number de- 

 pending to a large extent upon the size 

 of the mother. A female once delivered 

 seven, but I have a suspicion that she 

 devoured quite a few before I removed 

 them to another tank. For a successful 

 delivery I advise placing the female when 

 her greatly distended body when viewed 

 from above indicates that she is "ripe," 

 in a tank holding about four gallons, 

 which should be densely planted with 

 Sagittaria, Myriophyllum and Nitella. 

 The tank should have been standing sev- 

 eral months and have a good growth of 

 algae. The dense vegetation, especially 

 Nitella and Myriophyllum, will serve as 

 an effective shelter for the young. An- 

 other good plan is to place the female in 

 a spawning box. In any event the young 



