1148 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [6] 



tides of food which cannot find any other use should be given to tish, 

 and even then only exceptionally, always, of course, provided that the 

 fish will readily take to this food and derive some benefit therefrom ; 

 but even then one would always run the risk of polluting the water and 

 injuring the fish rather than benefiting them. 



To show incontrovertibly the usefulness of employing such artificial 

 food for fish, an Emil Wolf or Grouven would have to treat of this sub- 

 ject. As long as this is not the case, and all the results are based merely 

 on more or less arbitrary sui3positions, because in making experiments 

 the natural, vegetable, and animal food contained in the ponds has 

 nowhere been taken into account, it is better, for the present at leastj 

 to stick to the natural food, and to put the powerful productiveness 

 of nature to the best possible use. I would, in this connection, direct 

 attention to the easy way in which myriads of infusoria can be pro- 

 duced, and to the, unfortunately not entirely voluntary, production of 

 various kinds of flies, gnats, and other insects. So far, however, we 

 fish-culturists are very one-sided persons. If we are to fulfil our duty in 

 the highest sense of the word we must aim at being at the same time 

 raisers of insects, mollusks, «&c., so that we can at all times supply our 

 fish with healthy, palatable, and cheap food. 



I again appeal to the kindness of men of science, like Dr. Brehm, 

 Professor Semper, Professor Jaeger, and Professor Taschenberg, to 

 aid us with their observations and advice, whereby their highly inter- 

 esting and instructive studies will become of great practical value. 

 If we could get so far as to enable us to increase at will useful insects, 

 &c., and to limit the increase of the hurtful ones, our fish production 

 would reach a stage of which at jDresent we have no idea. 



There are other animals which, particularly the young ones, might 

 be used for fish-food, and I may be permitted to call attention to a 

 much maligned and misrepresented animal, and by showing its useful- 

 ness establish its reputation. 1 mean my old friend the frog, the large 

 green, croaking inhabitant of our stagnant and slow-running waters, 

 which tolerably early in the season produces young ones in every stag- 

 nant water. It has often been asserted that frogs are injurious to fish- 

 culture, because they are said to devour the young fry of fish, and 

 even competent authorities have in their books given methods for de- 

 stroying the frogs and their young ones. I know fish-culturists who 

 pay men to gather and kill the frogs, so as to* avert the damage which 

 they are thought to inflict. It is true that, like the fish of prey, the 

 frog has fangs, and that it is one of our most voracious, inquisitive, 

 and imprudent animals. Thus, by splashing in the water with a switch, 

 the large water-frog may be lured from the middle of the pond to the 

 edge, and, hoping to find a fish on the dry land or some other animal 

 in trouble, it advances blindly and boldly, so as even to jump on the 

 switch or the hand. The frog will devour any live animal that it can 

 swallow, and shows a special liking for small ca^rp, insects, larvae, snails, 



