15*11). Although histidine and methionine were present in greater amounts in 
Diets 6 and 9 than in the other treatment groups, no relationship is obvious 
between these amino acid levels and growth and survival. The higher amounts 
of leucine in the brine shrimp fed fish could indicate a role of this amino acid 
in their greater growth and survival. However, this was not evident in the 
freeze-dried brine shrimp fed group. 
No substantial differences were found in growth and survival of fish fed the 
nonsupplemented amino acid diet (Diet 8) versus the supplemented diet (Diet 
9). Therefore, it is difficult to say the quantity of dietary amino acids influence 
the metabolism and utilization of the various diets. Bioavailability studies will 
be necessary to ascertain the degree of incorporation of the supplemented 
amino acids. 
CONCLUSIONS 
1. The best growth and survival of juvenile silversides was obtained on a live 
3-day-old brine shrimp nauplii diet. Substantially lower growth and 
survival was obtained on the artificial diets. 
2. Freeze-dried brine shrimp provided less growth than a live brine shrimp 
diet. Live brine shrimp must contain some component which is removed 
or altered upon freeze drying. 
3. It is difficult to say whether protein (amino acids) in the diets was a 
factor in the differences in growth and survival of cultured fish fed the 
artificial diets and the brine shrimp fed fish. The brine shrimp fed fish 
did, however, contain higher levels of leucine than all other cultured 
groups. Bioavailability studies will be necessary to ascertain the degree of 
assimilation and incorporation of dietary amino acids. 
4. Whole body lipid fatty acid composition of cultured fish changed to 
reflect the composition of their diets. Fish fed the brine shrimp diet had 
higher fat levels and lower polyunsaturated fatty acid levels than wild 
fish. Cultured fish appear to be storing large amounts of lipids in order to 
obtain a threshold level of the polyunsaturated fatty acids. 
5. Fish fed a cod liver oil based diet more closely resembled their wild 
counterparts. However, growth and survival were poor compared to 
3-day-old brine shrimp fed fish. 
ACKNOWLEDGEMENTS 
The experimental part of the project required a close working arrangement 
between scientists of the marine fish culture team at the Environmental 
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