190 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



some iioisonous matter or mold may Lave attacked the eggs. Much 

 harm to the eggs and fry is done by the different enemies of fish and 

 hy the lish themselves. One spring I impregnated bass eggs and fixed 

 them on jnniper branches in wicker-work baskets, which were placed 

 in the water. For three days everything progressed favorably, but on 

 the fourth day I found in the baskets several thousand maggots, which 

 had completely devoured all the eggs. Later I took, for hatching- 

 young bass, boxes of fine wire-work, and arranged them in such a man- 

 ner that they did not touch the bottom but tioated in the water, but 

 even then the maggots collected in the boxes and ate the eggs off the 

 juniper branches. It seems, therefore, that these maggots scent the 

 fish eggs. Later they began to attack the young fry. After I had ob- 

 tained from these wire boxes quite a large qnantity of young fry — more, 

 in fact, than I was able to ship at the time — 1 placed some of them in a 

 l)uddle in one of my meadows, in order to observe their growth. But 

 I was not to enjoy this pleasure very long. The puddle was full of all 

 Koits of worms, one devouring the other, and all of them attacking the 

 ;\ oung I'ry of the fish as soon as they had become stronger than the fry. 



It should be remembered that young bass fry are so small and 

 transparent that during the first days they can hardly be seen with 

 the naked eye. In order to learn to know as many as possible of the 

 enemies offish, I put some specimens of every kind of aquatic animals 

 found in the jmddle in a glass and added some hake fry, which can be 

 seen better. At once a fierce war began, one endeavoring to devour 

 the other 5 but the fry seemed to be sought after by all of them. Thus 

 a salamander, three incheslong,had devoured in one hour about forty lit- 

 tle fiyli, both when taking in water and by pouncing upon them. Even a 

 heavy tadpole caught several little fish. Quickly moving and glittering 

 water-beetles and other insects devoured large numbers of fish, while the 

 maggots referred to above seemed to go more for the dead fish, and only 

 occasionally got a few live ones. Of the entire number of small animals 

 and fish, only the salamander and a few beetles remained as conquerors, 

 all tlie rest having been killed and devoured. 



l>ut, on the other hand, the fish themselves are not a whit better than 

 their enemies. Large fish will devour small ones, and their eggs are 

 most eagerly sought after by small and young iish. As young fish, 

 after they have lost their umbilical sac, principally eat small, almost in- 

 visible animalcules, as they grow they will take larger food, among the 

 rest the delicate fry of bass. If we consider these known and unknown 

 enemies, and other injurious circumstances, we can easily understand 

 why iji nmny years there is no increase in the number of fish, so that 

 the good years have to make up for the poor ones. 



KoLLNiTZ, December, 1885. 



