344 THE AQUARIUM 



reach. All tadpoles and snails should be removed, and pre- 

 cautions should be taken to free the tank of low forms of 

 life, such as hydras, which will devour the tiny young. If 

 the fry emerge safely, they will thrive on protozoans, and 

 later on small Crustacea and finely powdered dry food. 



Danio rerio, a native of Ceylon, is the commonest species. 

 It is boldly marked with broad stripes of brilliant blue, 

 which extend across the tail and anal fin, the ground color 

 being silvery in the females and yellowish in the males, the 

 distinction being more strongly noticeable during the breed- 

 ing season. Large specimens will average about an inch 

 and one-half in length. 



Danio malabaricus is an Indian form and the largest of 

 the genus. Its sides are bright blue, with three well- 

 marked, yellowish stripes. It is an exceedingly graceful 

 fish, and while less active than the preceding, is nevertheless 

 almost constantly in motion. 



Danio albolineatus is really one of the most marvelously 

 colored of fishes. Seen by properly reflected light its beauty 

 is indescribable, and just why it is not more commonly kept 

 is difficult of comprehension. When in full color, the entire 

 fish scintillates with flashing opalescent hues of great bril- 

 liancy, the females being somewhat less strongly colored 

 than the males. It is a species of lively disposition, and a 

 few individuals in good condition form a spectacle not soon 

 to be forgotten. 



The Labyrinth Fis'iies (Labyrinthini) form a group of 

 several families, all the members of which are distinguished 

 by the possession of air chambers, which supplement the 

 action of the gills in purifying the blood. By means of this 

 adaptation the fish is able, especially in the case of the 

 Climbing Perches (Anabas), to live out of water for some 

 time; but, on the other hand, if it be deprived of coming 

 to the surface to renew the supply of atmospheric air in the 



