82 COMMISSIONERS OF INLAND FISHERIES. 



they are not very well known to the public although quite well 

 known among fish culturists. 



When first hatched these fish do not resemble flatfish, but, like 

 most fish, are cylindrical in form and swim upright in the water. 

 After a certain period they begin to increase greatly in depth, and 

 when swimming turn partly on one side, at first showing no preference 

 for either side. Furthermore, they begin to rest upon the sides or 

 bottom of the cars containing them. The eyes gradually change 

 their position, and when the fish is from 6 to 8 mm. in length (\ to f 

 inches), the left eye has shifted to the right side. By this time a 

 number of radical changes, both in structure and habits, have taken 

 place in the fish. In its growth the increase has been mostly in depth, 

 and the fish become flattened. In the habits the changes consist 

 in ceasing to swim near the surface and remaining constantly close 

 to the bottom, usually lying on the bottom. Whether swimming or 

 resting it remains on the left side; because of the shifting of the eyes, 

 both are now on the right side, which from this time forms the upper 

 side. When disturbed, the fish will skim along rapidly for a distance, 

 and then settle in the sand, where its mottled appearance and semi- 

 transparency renders it very inconspicuous. It is now comparatively 

 safe from natural enemies. 



It is very apparent that in any attempt to propagate the flatfish 

 effort should be made to rear the larvae through this critical transition 

 period. The length of time required to pass the transition period at 

 W r ickford, in the latter part of April, 1910, varied between 16 and 20 

 days. This coming year your Commission intends to rear this species 

 through the transition period on a much larger scale. 



