i6o The Life Story of the 'Fish 



respective businesses, but at least during the few hours of 

 spawning each was conscious that the eggs existed, that certain 

 things had to be done in connection therewith, and that there 

 was another individual who played an important part in the 

 proceedings. 



Among aquarium fishes there are some which, v/hile still 

 releasing the reproductive cells of both sexes into the water, 

 take complicated measures to ensure the fertilization and de- 

 velopment of the eggs. Betta, the Siamese fighting fish, is a 

 well-known instance, and in this species, as well as in the 

 paradise fish and other near relatives, the male is the leading 

 spirit. When he feels the urge to spawn he advertises the 

 fact by building a "bubble-nest." This is a collection of 

 bubbles on top of the water, sometimes under a floating 

 leaf, sometimes in an open space between several leaves. To 

 construct it, the male comes to the surface, takes air into his 

 mouth, retires to the chosen spot, and there releases little 

 bubbles, one after the other, each covered with a sticky coat- 

 ing from his mouth which prevents it from bursting and 

 makes it adhere to the others. This process he repeats until 

 he has a dome of bubbles anywhere from one to two inches 

 in diameter and protruding sometimes as much as half an 

 inch above the surface of the water (see Figure 28). 



He then takes his post under his nest, and attacks all in- 

 truders. With gill covers projecting, with stiffened fins, and 

 with intensified coloring — all, it may be noted, tending to 

 make him look larger than he actually is — he sidles threat- 

 eningly up to any stranger. If the latter is a male, a fight 

 ensues in which the home-owner, through some submarine 

 working of the law of moral right, almost always wins. If 

 the stranger is an unripe female she flees j but if it be a ripe 

 female she refuses either to fight or to flee, and the only 

 thing left to do is to make love. 



The male swims around her and slaps her with his tail. 



