322 Modern Fishculture in Fresh and Salt Water. 



nests of twigs and the male takes entire charge of the 

 household. 



The male sea-horse, Hippocampus, has a pouch like 

 a marsupial, in place of an anal fin, in which the female 

 lays her eggs and he cares for them and their young. 

 The males of some tropical fishes are said to carry and 

 hatch the eggs in their mouths. 



CHAPTER XLVI. 



HOW FISH FIND THEIR OWN RIVERS. 



On this subject the late Professor James W. Milner 

 wrote some years ago in Harper's Magazine, and really 

 nothing more is known about it to-day. He said : "The 

 long held and only recently rejected theory that the 

 shoals of fishes moved in a vast mass along the coast, 

 sending off detachments into each river as they passed 

 its mouth, is to be attributed to John Gilpin and some 

 other authors, who have written flowingly on the sub- 

 ject. The recent careful investigations of naturalists 

 indicate that the anadromous fishes, those entering the 

 rivers and bodies of fresh water from the sea, do not 

 have an extended range in the ocean, and that each 

 river's colony remains, after returning, in the deep 

 waters opposite their river. The motive for the move- 

 ment of these shoals of anadromous fishes, or rather 

 how it is incited, has scarcely been explained. The 

 life of the fishes has always been a mystery. It is not a 

 search for food, as they do not eat while in fresh water ; 



