Andrews] THE KEEPING AND REARING OF CRAYFISH 297 



animals soon respond to foulness or to lack of oxygen in the water 

 and try to climb up to expose themselves to the air at the surface. 

 They resort to deep water chiefly for food and for protection. To 

 thrive in confinement the crayfish needs air and only enough water 

 to keep the body from drying up and to contain food. Hence, flat 

 dishes or sinks, or tubs, or aquaria with very shallow, running, water 

 will sustain an unexpectedly large amount of crayfish. Even when 

 there is no running water the crayfish will live many clays if allowed a 

 chance to expose its gills to the air at the surface. When large num- 

 bers are to be kept and a special receptacle has to be made a long 

 wooden box, painted inside with paraffine, is to be recommended. 

 If one end of the box be raised and water kept running through so 

 that the depth will grade from nothing at the inlet to a couple of in- 

 ches at the outlet end. the crayfish will have a range of conditions to 

 choose from. Porous bricks or tiles may be used to partition the box, 

 if desired, and also to make very acceptable climbing and hiding 

 places for the crayfish. If the sides of the box are not deep enough 

 to keep the crayfish from climbing out, some eight inches or more, 

 the box must be covered. 



When there is sunshine enough to make aquatic plants thrive a 

 few crayfish may be kept in balanced aquaria. Even C. Bartoni, 

 which is a native of cold brooks, was kept for months in a small 

 aquarium with abundance of living algae and Elodea, but with no 

 change of water. Small numbers may be kept in water which is 

 often changed by hand and also in aquaria aerated by air forced in. 



Next to abundant air supply the temperature is to be considered as 

 a factor in success if one is to keep large numbers of crayfish alive. 

 The lower the temperature the better for holding the stock through 

 the winter season, and at other times too high a temperature must be 

 avoided and extra areation insured when the water is unavoidably 

 warm. 



Eood is a matter of less imporfance as most of our crayfish are 

 dormant or inactive during a considerable part of the year and even 

 in the warmer seasons when they need food they can withstand long 

 fasts. In the spring they generally take food eagerly: «.'ggs. meat, 

 worms, potato, bread, crayfish flesh, molluscs, C'hara and other aquatic 

 water plants and algae, in fact most kinds of soft organic matter, will 

 often be consumed. A not inconsiderable amount of fine sediment, 

 or ooze, from the bottom of the aquarium is also co'lected and eaten 

 by crayfish that are kept in conditions more like those in nature. 



