1120 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [20] 



wliich should be particularly well protected aud have an abundant sup- 

 ply of water. 



In the winter-ponds proper, but still more so in the ponds of older fish 

 when used as winter-ponds, frogs and toads should not be allowed in 

 any considerable number, because in early spring they cause the sick- 

 ness and death of a large number of fish, by settling on their heads and 

 placing their-fore feet on the eyes of the fish, thus sometimes prevent- 

 ing them from taking food for weeks. Old carp-raisers who were well 

 acquainted with such occurrences, thought that the frogs ate the eyes and 

 brain of the carp, or sometimes used the carp as a horse, to carry them 

 quickly to some good feeding-place where they would snatch the food 

 from the moath of the poor fish. These explanations are entirely erro- 

 neous. The male frogs and toads — and only such are found on carp — 

 will often sit on the females for weeks before spawning, so as to im- 

 pregnate the eggs the moment they are laid. The sexual desire of the 

 male frog is so strong that he will not even let go of a dead female, and 

 if no female can be found, he will even mount another male frog or any 

 other object that comes in his way. The head of the carp, which during 

 the si)awning season of the frogs is still in a sort of torpor, appears to 

 the frog as a very suitable object for his purpose, and when the ponds 

 were drained in spring hundreds of carp, and sometimes even trout, 

 were found with frogs firmly adhering to them. 



Another most dangerous enemy to the fish in the winter-ponds is the 

 otter, which, when a favorable opportunity presents itself, will kill more 

 fish than it can devour, and which, if found in large numbers, may de- 

 stroy the entire stock of fish. A constant watch should therefore be 

 kept for any traces of this bitter enemy of the carp. 



5. The stock-ponds. 



The stock-ponds are small basins, frequently with brick or wooden 

 walls, having an abundant supply of water, which serve for keeping 

 those fish which are shortly to be sold. Their bottom should be of clay. 

 If they have a sufficient supply of water, and if the fish are not to stay 

 in them for any great length of time, they may be stocked at the rate 

 of 50 kilograms carp per one square meter. 



6. The pond-fisheries. 



During summer — apart from the transplanting of young fry necessary 

 in Dubisch's method — one should not fish in the carp-ponds with nets, 

 because this disturbs the fish, most of which, moreover, either slip away 

 under the net, or leap over it. Fish may, however, occasionally be 

 caught, when they are needed, with fish-pots, or with hooks and lines, 

 unless one should prefer to construct small stock-ponds for keeping the 

 fish intended for home consumption. In such stock-ponds the fish must 

 of course be fed, and can easily be taken with a small purse-net. 



