LIVING FISHFOODS 135 



rusty red. The color varies from this to olive and gray. Fish breeders 

 like to see the daphnia as bright a red as possible, although it is an open 

 question as to whether the red ones are better food. The same individuals 

 will alternate in color, probably due to a difference in food. Usually these 

 crustaceans are not so plentiful as to color the water, and we have to use 

 our eyes more closely to locate them. The collector should provide him- 

 self with a cheesecloth net about 12 inches in diameter and 15 inches 

 deep, fastened on a pole or jointed handle not less than 6 feet long. If 

 an examination of the water does not at first reveal any daphnia, the net 

 should be tried anyhow, using a gentle stirring motion back and forth, to 

 stir up the bottom water. Daphnia have very peculiar habits, and one 

 can never tell from day to day just how they are to be found, so that 

 the collector will always have to depend somewhat on his own resources. 

 If an examination of the net after dipping for a few minutes shows noth- 

 ing, try elsewhere. If a swarm has been located do not take too many 

 into the net at one time, as the weight of the top ones crushes those 

 beneath. A mass that would bulk about equivalent to an orange should 

 not be exceeded. Reverse net into pail of water and repeat until the 

 water is thick with daphnia. In cool weather the pail may be carried in 

 this crowded condition for about an hour. If the day is hot, a piece of 

 ice should be added to the water — enough to keep temperature down until 

 home is reached. Newspaper wrapped about the can helps the ice melt 

 more slowly. As soon as home is reached, add fresh water to the pail 

 and transfer the daphnia to tubs or tanks kept for the purpose. Like fish, 

 the water they are in should have as much air surface as possible. Do 

 not try to keep too many in stock, as overcrowding suffocates a number 

 and these, in turn, decomposing, kill the living ones. The cooler they 

 are kept, the longer they will last. In hot weather they can be kept about 

 three days and in October about two weeks. 



In transferring from carrying pails to stock tanks it is well to first 

 pour in small portions to a white enamel basin which enables one to 

 carefully go over the catch and remove any insect enemies. (See page 

 143.) If the daphnia are too thick to be readily examined, some water 

 should be added. A little care in keeping out the enemies at the start is 

 energy well invested. Most of the enemies and the dirt may be sifted 

 out (under water) by using a screen just large enough for the daphnia to 

 pass through. 



A beginner will do well to make the acquaintance of an experienced 

 daphnia collector and go along with him on a trip. There are now 

 aquarium societies in many of the large cities, part of their activities 

 being the dissemination of such knowledge. All those interested 

 should have active or corresponding membership in such an organiza- 

 tion. 



