Fish as Nest-builders. 



surface of the water and suck in a mouthful of air. He 

 holds this in his mouth for a while, and then permits 

 it to escape and rise to the surface of the water in the 

 form of a bubble. This process is repeated again and 

 again, until a regular collection of bubbles has been 

 formed, all clinging together in a mass some three or 

 four inches in diameter. The bubbles do not burst, 

 for each one as it was formed within the mouth of the 

 little fish received a coating of slime or mucus secreted 

 by special glands, so that they are really miniature 

 bladders more than bubbles, stuck closely together. 

 Having completed this strange nest, the little Paradise- 

 fish goes forth in search of a wife, and soon returns 

 with her, and induces her to spawn beneath the shelter 

 of the raft-nest. 



The eggs of the Paradise-fish are very buoyant, so 

 that as they leave the female they do not sink, but float 

 upward and stick to the under surface of the raft-nest. 

 All the time that the little female is depositing her eggs, 

 the male is in a great state of excitement and watchful- 

 ness, in case any of the precious eggs should go astray ; 

 and should one float away beyond the nest, he will at 

 once give chase, and bring it safely back in his mouth, 

 like a dog returning a lost ball. He is by no means 

 contented with one wife, and several females will be 

 brought in succession to deposit their spawn beneath 

 the raft-nest, until some five hundred eggs may be 

 collected beneath it. Then, like the male Stickleback, 

 the little male Paradise-fish mounts guard while the 

 ladies depart to enjoy themselves. Not for one instant 

 does the devoted little fellow neglect his duty, and it is 

 very pretty to see, with what care he tends the eggs, 



61 



