38 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



The relation between total production per 

 female and bottom area (square feet) per male 

 is shown in figure 11, while the total production 

 per female in relation to bottom area per indi- 

 vidual is shown in figure 12. From table 11 and 



BOTTOM AI1£A(S0.FT.I PER MALE 



Figure 11. — Total production per female in relation to 

 bottom area (sq. ft.) per male. (Total stock in 

 parentheses.) 



figui'es 10 to 12, it may be seen that the tanks with 

 50 fish or less (except tank 10) had a much better 

 production than those with more, while an allow- 

 ance of 4 square feet of bottom area per male 

 and 1 square foot per individual gave the highest 

 production per female (see tank 5, table 11). 



The analysis of variance showed that the differ- 

 ences in fry production with respect to the con- 

 centrations, 30, 50, 70, and 90 fish, used in the 

 experiment were significant {F = 11.44, P < 

 0.01) . There was also a significant interaction be- 



tween sex ratios and brood-stock density, indicat- 

 ing that the production resulting from any spe- 

 cific ratio did not vary in a unifomi manner with 

 respect to availability of space. 



DIET AND REPRODUCTION 



Early attempts to assess the qualities of differ- 

 ent types of feed in i-elation to f ly production at 

 the pilot plant proved inconclusive, owing to dis- 

 similar conditions in the brood tanks (tanks 1 and 

 3) . However, we were able to observe the general 

 acceptability of the five types of feed tliat were 

 used. 



Finely ground feed, such as rice bran and 

 chicken mash, was fouiid to be unsuitable for the 

 adults as they cannot strain small particles from 

 the water. Much of the feed was wasted and 



y 300 - 



BOTTOM AREAISQ.FT.I PER INDIVIDIJAL 



<'iouKE 12. — Total production per female in relation to 

 bottom area (sq. ft.) per individual. (Total stock in 

 parentheses.) 



Table 11. — Sex ratio and concentration of brood stock and production of fry, September- November, 1958 



