206 BREEDING GOLDFISHES 



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at one end and small lump in the centre. This lump is the yolk-sac and 

 serves as subsistence for the first few days. At first the alevin can only 

 swim by a few jerky motions, and has the power of sticking wherever it 

 touches. At the age of one day they are to be found hanging on the 

 plants and the sides of whatever receptacle they are in. In from two to 

 three days they are swimming freely. When the yolk sac has been 

 absorbed, which is in about three days, the babies will need some food 

 which has been previously prepared. The first natural food is a large 

 variety of microscopic animals known under the general heading of in- 

 fusoria. These are present in all exposed water which has stood a few 

 days, but in order to have sufficient for fish food it is necessary to have 

 conditions favorable to their culture. This consists mainly of vegetable 

 decay. Dried and powdered lettuce or duck-weed leaves or pea flour, 

 sprinkled thickly on the water, produce good results in a few days, kept 

 in a warm place and a subdued light. Also a quantity of hay over which 

 boiling water is poured will soon produce the creatures. Decaying leaves 

 of aquatic plants are very good for the purpose. A low-power microscope 

 or cheap magnifying glass should be employed in this work. (See page 

 128.) After the culture is apparent and the fish are swimming freely, 

 occasionally dips of culture water should be put in with the young fry. 

 Sometimes the infusorians can be found freely in standing pools, particu- 

 larly where the water is not very clean, and where there are no cyclops 

 or other carnivorous crustaceans. A rotifer, Brachionus rubens, some- 

 times occurs so thickly that the surface of the water appears to be cov- 

 ered by a thin, rusty scum. When such a scum is observed in a stagnant 

 pool some of it should be placed in a small bottle and observed with a 

 low-power magnifying glass. If there is the appearance of dust-like par- 

 ticles moving continuously about, it is very likely they are rotifers. A 

 thimbleful of this yellowish water which has been skimmed from the sur- 

 face contains more rotifers than several gallons of ordinary stagnant 

 water, and the breeder who can locate this kind of live food when his 

 fish are from one to three weeks old is in good luck. Very small live food 

 tends to keep the young fishes more nearly a uniform size. If daphnia are 

 fed at first, it is only the more robust individuals that can eat them, and 

 the result is a rapidly increasing disproportion in size that soon ends in 

 cannibalism, unless the young giants are promptly placed by themselves. 

 Small pools about a cattle yard are particularly favorable to infusoria and 

 rotifera, but, of course, if the water is very dark it should be used spar- 

 ingly. This sort of food should be used for about ten days to two weeks. 

 Illustrations in figure 109 show types of this living food, but one does 

 not need to be very particular as to the exact form. In general, anything 

 alive that is too small to be well seen by the naked eye, but which is 



