306 - 
bulletin OF THE UNITED STATES FISH COMMISSION. 
EXPERIMENTS WITH ARTIFICIAL PROPAGATION OF MINUTE CRUSTACEANS.* 
By Dr. W. Kochs, Univirsi/y of Bomt. 
Within the last tweutj" years fish-cnlturists have become more and more convinced that tne 
knowledge and dissemination of minute crustaceans and other lower animals inhabiting fresh water 
are of the greatest benetit to fishing. The growth of the young brood and the faculty of the full- 
grown fish to increase under favorable conditions are in the first instance regulated bj" the facility of 
obtaining good food, and this regularly and abundantly. Emil Weeger delivered a-n interesting lecture 
on this subject at the International Agricultural and Forestry Congress at Vienna in 1890, which 
was later published with illustrations showing “ strongly magnified representations of several species 
of crustaceans frequently found in the waters of central Europe and insects belonging to the family 
of gnats. May flies, and dayllies, all serving as food for fishes.” 
At the close of this lecture Victor Burda, fish-culturist of Bielitz, spoke on the same subject 
and added, relative to the propagation of fish in large ponds, that these small infusoria were not only 
of the greatest importance for salmon-breeding, as stated by Weeger, but also for carp-breeding; it 
was a subject which would demand the greatest attention among experts, because it was known ever 
since the well-known expert. Director Lusta, had lifted the veil behind which the question of the 
nutrition of the carp had been screened for so long a time, that the j)iincipal food of the carps, like 
that of the salmon, not only in its earliest stage, but also later, consists of animal life, and he asks 
why the artificial breeding methods of the water fauna, as suggested by Weeger, should not be 
adoj^ted. 
Mr. Burda then continues ainl points out some measures by which the j)ropagator might exert a 
beneficial influence upon the growth of this minute water fauna. Starting from the idea, and this 
idea is correct, that the minute crustaceans live on infusoria, and that these infusoria again thrive on 
plants in the process of decomposition and on animal life, he endeavors to supply the ponds with the- 
necessary and appropriate food. He says : 
“ The decomposed substance serving as food for the infusoria accumulates on the bottom of the 
pond, and is also mechanically distributed in the water, giving it a muddy appearance. The substance 
distributed in the water partly originates on the bottom, partly enters the pond with the new influx, 
in which case it comes from the soil, near by or far off, according to the condition of land or water. 
The more luxuriant and the more fertile the land the richer the ingredients washed into the pond. It 
is, therefore, of the greatest importance to have the greatest amount of this muddy influx led into 
the pond after a heavy rainfall.” 
This IS doubtless correct, but it is also a fact that this acquisition to the pond is gained at the- 
expense of the surrounding lands, because they are impoverished by the heavy rainfalls. Of course 
considerable values in the shape of organic and inorganic substances wash from the fields into the 
brook, from there flow into the rivers, and then into tlie ocean, and so would become lost if they 
were not collected in the ponds and subsequently absorbed by the fishes. But a correct pond 
propagation must not depend on circumstances; just as a certain quantity and quality of manure 
must each j^ear be supplied to the field to produce fair crojis, so the same action must be taken in 
regard to the fish ponds. Dr. Kochs tried for a year to catch the crustaceans described on Weeger’s 
plates and to breed them in glass vessels holding from 8 to 10 liters (1 liter is equal to 2.113 pints) 
for the purpose of investigating their conditions of life. He found them only in puddles, which 
received their fertilizing substance from the surrounding land or from animal cadavers. In one case, 
in a puddle in a clay pit near Wiuterschlick, he found that dung particles had been washed into the 
puddle from an adjoining sloping orchard, where numerous dung heaps were found. The consequence 
was a luxurious vegetation and numerous crustaceans in this puddle, while in many other adjacent 
puddles hardly anything living could be detected. 
It is not essential to catch a great number, because they increase wonderfully. To obtain those 
species in a perfect condition, which collect between the water plant.s, he used a pear-shaped pipette 
holding 1 liter, having a long and strong, but narrow, neck, and on the other end, in the pear, an 
aqierture 1 centimeter wide. When, closing the narrow neck and placing the pear end of the vessel in 
the water, the stopper is suddenly removed, the water will rush into the vessel, carrying with it the 
small infusoria. It is not possible to catch nearly as many with mull netting, besides the latter is 
unserviceable betw'een the water plants, and it is difficult to separate the infusoria from it. 
Dr. Kochs has jirepared since .June, 1891, a number of glass vessels as aquaria, in each of which he 
placed all kinds of crustaceans. Some he kept at his private residence in the open air and during the- 
Translated by H. H. Gerdes from Biologisches Centralblatt, Band xii, pp. 599-606. 
