230 



FISH HATCHERY MANAGEMENT 







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Figure 73. Gill lamellae from (l) a normal and (2) a pantothenic acid-deficient 

 rainbow trout. Hyperplasia of the epithelium has resulted in fusion of most 

 lamellae (arrow) on two filaments of the pantothenic acid-deficient trout. (Cour- 

 tesy Charlie E. Smith, FWS, Bozeman, Montana.) 



animals for growth and various metabolic processes. As mentioned, fish 

 also use mineral salts and ions to maintain osmotic balance between fluids 

 in their body and the water. 



Many minerals are essential for life, but not all are needed in the same 

 amount. Seven major minerals are required in large amounts and constitute 

 60 to 80% of all the inorganic materials in the body. The seven are calci- 

 um, phosphorus, sulfur, sodium, chlorine, potassium, and magnesium. 



