WHOLESALE BREEDING 



67 



has several advantages, among which is interchangeability of screens 

 or covers. Allowing 6 inches for the thickness of bottom will leave 

 an inside depth of 20 inches, but under ordinary circumstances they 

 should not be filled beyond 14 to IS inches. With the outside tanks 

 this gives a safety margin of several inches before a heavy downpour 

 of rain causes the level to rise to the screened safety overffovvs one 

 inch from the top. It also catches practically all of the rainwater of 

 the season, which is excellent for the fishes. If the water becomes 



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Fig. 53. Wholesale BREEorNo Establishment, Showing Greenhouse and 

 Outdoor Concrete Tanks 



nigh, it can be siphoned off from the bottom until original level is 

 reached. The advantage of being able to fill up, if necessary, to 19 

 or 20 inches in an inside tank is that at certain seasons the greenhouse 

 capacity for fishes is taxed to the fullest. At such times the extra 

 volume of water for the storage of fish stock will be keenly appre- 

 ciated. An economy of space can be eft'ected by building wooden 

 tanks to stand over the section marked "Breeding Ponds" in figure 53, 

 thus making two rows here instead of one. The wooden tanks should 

 be somewhat narrower than the lower concrete pools. 



