460 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



The purpose of the bubbles — to serve as a nest for the eggs and a hover for the 

 newly hatched young — is admirably achieved. As the bubbles gradually lose 

 their stickiness and become scattered or ruptured, one may observe the male con- 

 stantly engaged in renewing the supply. 



If one day a mature female fish is introduced into a vessel with a male fish 

 that has been blowing bubbles, the probability is that next morning the bubble 

 mass will be found to contain several hundred minute transparent eggs not easily 

 distinguished from bubbles without a magnifying glass. 



At egg-laying time the fishes consort near the surface, and at short intervals 

 the eggs are extruded in small batches. As the eggs slowly sink toward the 

 bottom, both the male and the female fishes go after them, gently take them in 

 their months, and returning quickly to the surface blow the eggs into the bubble 

 nest, repeating the performance as often as may be necessary to gather up all 

 the eggs. This continues for several hours until all the ripe eggs have been 

 voided. 



The role of the mother fish is almost entirely restricted to the production of 

 eggs. After the eggs are once placed in the nest, her family duties cease, and 

 all subsequent care of eggs and young devolves wholly on the male. 



The fish is rather prolific. At one spawning period from 200 to 700 eggs may 

 be expelled, the average number for a fully developed normal fish being 400 to 500. 

 A month after one batch of eggs has been produced, a given female may be ready 

 to yield another lot, so that in the course of a year one fish may be responsible 

 for 2,500 to 5,000 or more eggs. 



Aided partly by capillary attraction, partly by the viscidity of the bubbles, the 

 eggs are held in the nest until hatching ensues. The incubation period is re- 

 markably short, covering only 30 to 40 hours in water at 80° to 85° F. Should any 

 of the eggs drop from the nest and fall to the bottom, the male recovers them and 

 blows them back. 



The newly hatched fishes find shelter under the bubble nest, and remain there 

 while their yolk sacs are being absorbed and their fins are developing. If they 

 stray from their proper place before they are old enough, the male carries them 

 back to the nest and gently ejects them ; and during the entire period of infantile 

 helplessness the male repeatedly takes the young in his mouth and blows them 

 out with new bubbles, thus insuring proper oxygenation. 



Throughout the nesting period the male fish is extremely busy and his vigilance 

 never relaxes. In addition to making and maintaining the bubble nest, replacing 

 eggs that may drop from the nest, rounding up the straggling young, and mouth- 

 ing the young at iutei"vals, he is constantly on the alert to protect the eggs and 

 young from intruders that may devour them. The chief offender is the mother 

 fish. In a wild state, she can be forcefully driven off and kept at a distance, but 

 in the restricted quarters of an aquarium she must be removed as soon as egg 

 laying is completed. 



The presence of the male seems to be essential in the development and hatching 

 of the eggs. If the male is removed from the aquarium, the eggs, or most of them, 

 will fail to hatch. Those that fall to the bottom will suffocate ; while the vitality 

 of those that remain in the nest may be impaired by the lack of the aeration that 

 comes from mouthing and bubble blowing. 



It is of interest to note that the forbearance of the male from eating the eggs 

 and young is not due to any temporary impediment to his digestive powers, such 

 as a ijhysiological closure of the esophagus. He can and does eat mosquito larvae 

 throughout his period of guard duty. 



