590 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [124] 



not be kept in winter ponds with carp. On small pond farms it may be- 

 come necessay to keep carp of diiferent ages in one and the same winter 

 pond. In that case it will be well, with a view of preventing an un- 

 necessary delay caused by the sorting of the fish and a consequent de- 

 lay in the fisheries and the transfer of the fish to the raising ponds, to 

 place in one winter pond only fish whose age can easily be distinguished. 

 As a rule, the three years' fish are immediately after the autumn fisher- 

 ies transferred to the stock ponds ; but there may be cases when this 

 transfer cannot be made at that time, and when these fish have to be 

 wintered. In placing these fish in the winter ponds great care should 

 be exercised to arrange matters so that the different classes of fish can 

 easily be distinguished in spring. If the quality of the ponds varies 

 very much it will be exceedingly diflQcult to distinguish the one year's 

 fish from two years' fish, and these from three years' fish. Young fish 

 which for some cause have been retarded in their growth are frequently 

 not any larger during the first year in the raising ponds than young 

 fish which have enjoyed greater advantages at the the end of their first 

 year. In such cases the one year's fish and the three years' fish should 

 occupy the same winter pond, and the two years' fish should share a 

 winter pond with the stock carp (in case these have to be wintered). If 

 the space is limited and if the pond farm is so small as to possess only 

 one winter ])Oud, nothing remains to be done but to i)ut all the fish in 

 this pond, and sort them as well as possible in spring. It will, however, 

 in that case be almost impossible to prevent fish of different classes 

 from getting into one and the same raising pond. 



In view of the great importance of successfully wintering fry and 

 young fish, the winter ponds should be under constant supervision 

 during all winter, as in severe winters the great cold, deep snow, 

 and especially the freezing of the pipes or ditches through which the 

 water enters and flows out, may prevent fresh air from entering the 

 pond, and may cause a vitiation of the water, owing to the lack of 

 oxygen, which may prove fatal to the fish. The entire contents of a 

 winter pond may be lost if fresh water is not introduced constantly 

 and if no holes are made in the ice. If the supply of fresh water is 

 irregular, especially in sky ponds, or when winter ponds have been over- 

 stocked, there will invariably be great danger that the fish will perish 

 during an exceptionally severe winter. I repeat, therefore, that the 

 overcrowding of winter j)onds must be avoided. 



Horak mentions the following indications of api)roaching danger: 

 '■' The first indications of danger, which is particularly great during the 

 latter part of winter, are small air-bubbles which make their appear- 

 ance in the holes in the ice ; the water begins to change its natural color; 

 it is no longer clear, but of a brownish-yellow or whitish color, accord- 

 ing to the different soil and mud. This change of color is also fre- 

 quently caused by microscopic plants and animals, which increase with 

 incredible rapidity and at an enormous rate. Before the fish aiJpear 



