Table 15-8. Percent Survival and Weight Gains for Silversides 
Cultured on Various Experimental Diets 
(Modified from Beck and Poston (7))^'^ 
Survival 
Weight Gain 
Experimental Diet 
% 
mg 
% 
1. Wild plankton 
54.0 
4.3 
48.3 
2. Brine shrimp-live 
97.0 
36.6 
411.2 
3. Starved 
0.0 
— 
— 
4. Brine shrimp-dried 
66.0 
4.5 
50.6 
5. Tetra Marin 
95.0 
4.4 
49.4 
6. Artificial, HPM-1 
51.0 
0.6 
6.7 
7. Artificial, CHP-1 
28.0 
1.2 
13.5 
8. Artificial, MP-1 
65.0 
-0.7 
-7.9 
9. Artificial, MP-2 
61.0 
-0.5 
-5.6 
Diet #1 data only one replicate, diets 2, 4-9 are averages of two replicates. 
2 
Fish were 23 days old at onset of the study and were cultured for 23 days. 
percent) and the best weight gain (411 percent). Normal growth of the wild 
fish has been estimated at 12 mm per month during the growth period (6). 
None of the other diets gave an appreciable weight gain; in fact some groups 
actually lost weight. With the exception of Tetra Marin, all the artificial diets 
produced a relatively poor survival rate. 
Table 15-9 shows the fatty acid composition of the natural and artificial 
diets. The effect of the dietary fatty acids on the cultured fish lipids is 
presented in Table 15-10. The diet profiles and the respective cultured fish 
profiles were quite similar. The cultured fish fed the cod liver oil based diets 
(Diets 6, 8, 9) and those fed Diet 5 contained a much higher level of 22:6co3 
than the brine shrimp fed fish (Table 15-6 and 15-10) or the soybean oil fed 
fish (Table 15-7 and 15-10). These fish more closely resembled their wild fish 
counterparts. A lipid modification of the salmon diet had therefore effected a 
biochemical change in the fish to a more “wild like” laboratory fish. The 
replacement of the soybean oil in Diet 7 by cod liver oil (Diet 6) doubled the 
survival level, however growth was only one-half as great. It is very difficult to 
draw and direct correlation between the dietary lipid composition of the 
various diets and survival, since the experimental design of this study was quite 
unlike the classical nutrition experiments. 
The comparison of the amino acid profiles of fish fed the natural and 
artificial diets indicated little variation between the treatment groups (Table 
225 
