G02 REPORT OF COMMISSIONEE OF FISH AND FISHERIES. [136] 



According to Meyer, infusoria may easily be procured in the following 

 manner : " Take a large glass vessel, put at the bottom fresh leaves and 

 other parts of plants, on f he top of these some animal excrements (par- 

 ticularly those of cattle), and on these another layer of leaves, fill up 

 with water and phice in the sun, when in a very short time an enor- 

 mous Lumber of small crustaceans and infusoria will develop, which 

 form the favorite food of young trout. To use these diminutive animals 

 for trout food, a quantity of the animated water is filtered through a 

 small dipper of mull, by which process a residue is left, which on close 

 examination is found to be composed of thousands of animalcules." * 



lU'ibre another spawning period commences, the one-year-old trout 

 are t;iken to the raising ponds, and the ditch is given a thorough clean- 

 ing. As to the general requisites of raising ponds the necessary in- 

 formation lias l)een given in a previous chapter. As regards their 

 dei)t!i it should be stated that for one-year-old trout it should be 60 cen- 

 time! eis, for two years' trout 120 centimeters, and for older trout 1.5 me- 

 ters, wiiicli is also a sufficient depth for wintering trout. If the fish 

 in the i aisiug- and stock ponds are not to be fed artificially, their num- 

 ber will be determined by the quantity of natural food contained in 

 these ponds. If it is necessary to use artificial food, it will be best, to 

 ]nevent any pollution of the water, to use only live animals, such as 

 maggots, fish fry, worms, &c. Besides vegetable food, animal food may 

 also be introduced into the ponds by adding to the trout some small fish, 

 such as loach, minnows, &c., whose fry serves as food for the trout ; but 

 this method will have the disadvantage that these fish will devour 

 many of the worms and insects which were intended for the trout, and 

 on the whole, therefore, it cannot be recommended. To use scraps of 

 meat as food can be only recommended if the quantity is very small and 

 in suiall tanks, so that it can be eaten up at once, and, if necessary, the 

 remainder can easily be removed from the water, which otherwise is 

 aj)t to become polluted. Von dem Borne says that the time when the 

 trout is most voracious is in spring, while in hot weather it eats but lit- 

 tle. During the spawning season, and during winter when the temper- 

 ture reaches zero (R.) [32^' F.] trout do not eat anything. Trout should 

 therefore never be fed during the noonday heat, but early in the morn- 

 ing and in the evening. As for the rest, all that has been said regard- 

 ing cari)culture also applies to trout-culture, of course with such modi- 

 fications as the nature of the trout demands. 



11. SALMON {Trntta salar), SEA TROUT {Triitta tnilta), AND LAKE TROUT 



(Truila lacustrifi). 



We cannot i)roperly speak of culture as regards those kinds of fish 

 whose young are not produced on the j)ond farm, but have to be ob- 

 tained from abroad. To the keeping, therefore, of salmon, sea trout, 

 and lake trout, all that has been said relative to trout-culture will apply 



Meyei-, I'rakiifichtr Fiiicli.:i(chler, \y. 62, 



