FISHES IN RELATION TO MOSQUITO CONTROL. 7 
The pond was already well stocked with Gambusia, and it doubt- 
lessly possessed conditions suitable for the propagation of the top 
minnow, but probably not for that of sunfishes. However, there 
were present before stocking a few sunfishes. The bottom of the 
pond was very muddy, the shore edges were almost free of vegeta- 
tion, there was little alge, and the water was quite foul. Nearly all 
of the sunfishes lived, so far as known, and the top minnow made a 
notable increase during the summer. It undoubtedly is true that 
Gambusia is not as abundant in this pond with the large number of 
sunfishes present as it otherwise would have been, but the experi- 
ment certainly shows that the bream is not very destructive to the 
top minnow. 
Gambusia in a few instances needed protection from natural en- 
emies, but much more generally from man. The top minnow had 
become quite a favorite bait for larger fish, and wherever this fish 
was fairly common, fishermen and bait collectors were frequently 
seen catching it with small seines and dip nets. This practice quite 
certainly did more than any other one thing toward preventing Gam- 
busia from becoming more abundant. Consequently, it was thought 
advisable to publish a notice in the local newspapers, explaining that 
this fish was useful in destroying the wiggle-tail and asking fisher- 
men to kindly discontinue using it for bait. In addition, a placard 
was posted at each pond, stating that the small fish were protected 
as a health measure and that they were not to be used for bait. The 
response to these requests was most cordial, as not an offender was seen. 
Several ponds with steep shores provided very little shallow water 
and the top minnow did not thrive. These ponds supported larger 
fish, including the large-mouthed black bass, and it is believed that 
they destroyed the minnows. The chief protection which Gambusia 
finds from the larger predacious fishes, appears to be shallow water. 
An effort, therefore, was made to provide this protection in the 
above-mentioned ponds by grading the shore at several points in 
each pond. The difficulty encountered in the pond in Allen Park 
has already been mentioned. This greatly overstocked lake was 
seied, and a large number of predacious fishes were removed. It 
was then restocked with Gambusia, and after that, bass were not 
observed feeding on the top minnow. The provisions against nat- 
ural enemies were made too late in the season to bear very evident 
results during the present investigation. 
MEANS AND METHODS EMPLOYED IN STOCKING PONDS WITH 
GAMBUSIA. 
Minnows for stocking ponds were secured mainly from two sources; 
first, from swamps within the protected area which were being 
drained; and second, from waters outside of the extra-cantonment 
zone, from places where minnows did not appear to be needed. 
Large numbers of minnows were secured from these sources and 
placed in ponds where few or none were present. 
One pond, about 100 by 30 feet, with an average depth of about 
3 feet, was used as a “‘hatchery.” This pond has a very muddy 
bottom and it supports much alge and several attached plants. 
All fish were removed from this pond. Then a partition, composed 
160695°—20-——28 
