ARTIFICIAL PERCH CULTURE 231 



running water, without good results ; but when the 

 eggs were exposed to the light, as they would be in a 

 river, they hatched out very satisfactorily. But, as I 

 have said, I found them very difficult to remove from 

 river or pond before they were fully eyed. 



The difficulty of confining newly hatched perch fry 

 in any box is considerable. I could find no zinc 

 with sufficiently fine perforations for the purpose, for 

 a young perch is a little, fragile, transparent thread of 

 a thing which appears to be able to go through the 

 smallest aperture. Finally I defeated him by putting 

 two flannel screens, a foot apart, at the end of the box, 

 filling up the space between with clean sand. I had 

 to have a trickle of water running into the box to 

 keep the temperature down, for, working the apparatus 

 out of doors in the sunlight, I found the water was 

 apt to get hot in the day time, and, rightly or 

 wrongly, considered that great changes of temperature 

 would be harmful to the fish. 



If perch culture is to be prosecuted on a large scale, 

 I have no doubt that the ponds ordinarily used by 

 trout culturists would answer the purpose, but they 

 might with advantage be somewhat deeper than are 

 used for trout, with shallows at one end. There 

 would have to be an abundance of natural food in 

 them, for it is doubtful if ordinary fish food could be 



