238 FISH HATCHF.RY MANAGEMENT 



physical conditions (moisture, heat, light); oxidation; micro-organisms 

 (molds, bacteria, yeast); and enzymatic action. 



Feed in bags or bulk should be stored in a cool, dry area. Low humidity 

 must be maintained because moisture enhances mold growth and attracts 

 insects. Molds, which grow when the moisture is 13% or above, cause feed 

 spoilage and may produce toxins. High temperatures may cause rancidity 

 of oils and deterioration of vitamins. Rancid oils can be toxic, may destroy 

 other nutrients, will cause off- flavor of the feed, and will produce an un- 

 desirable flavor in fish eating the feed. The storage area should be kept 

 clean and adequately ventilated. The stored feed should be protected from 

 rodents, insects, and contamination. 



Ideal conditions for storing bagged dry feed include stacking the bags 

 not over ten high on pallets so the bags are 3 to 4 inches off the floor. 

 Space should be provided between the stacks for air circulation and rodent 

 control. Low relative humidity and low temperature in the storage area 

 reduce the rate of deterioration in feeds. 



The recommended maximum storage time for dry pelleted feeds is 

 90-100 days. If less than optimal storage conditions exist, the storage time 

 should be shortened. 



Bulk feed should be stored in clean bins free of contaminants or spoiled 

 feed. The bins must be in good condition to protect the feed from water 

 and weather elements. Bins located in shaded areas remain cooler. Bins can 

 be fitted with a screening unit on the discharge to remove dust and fines 

 from the pellets. In many cases the fines can be returned to the feed mill 

 for repelleting or be used to fertilize ponds. 



Moist pellets should be stored in the freezer at temperatures below 0°F 

 until they are to be fed, then thawed just prior to feeding. 



Feed Evaluation 



The performance of feeds often is measured to evaluate or compare them. 

 The measurements used to evaluate feeds at production hatcheries are: (l) 

 fish growth (weight and length); (2) feed conversion; (3) cost to rear a 

 pound of fish; (4) protein and calories required to rear a pound of fish; and 

 (5) mortality and dietary deficiency symptoms. 



Feeding 



Feeding once was considered a simple task and was usually assigned to the 

 least experienced fish culturist. The chore consisted of merely feeding all 



