6 FISHES IN RELATION TO MOSQUITO CONTROL. 
sexually mature and produce young when four to five months old. 
The later broods of course do not produce young until the following 
season. 
The general plan pursued in testing the practical value of the top 
minnow in antimalarial work may be divided into three principal 
lines of activity, viz: First, that of protecting Gambusia in the area 
in which the tests were to be made; second, that of increasing the 
number of top minnows in the ponds in which the mosquito nuisance 
was to be abated by means other than protection; and, third, that 
of making careful field observations. 
THE ABUNDANCE OF GAMBUSIA, ITS ENEMIES, AND HOW IT WAS 
PROTECTED. 
The top minnow was present in nearly all of the older ponds, doubt- 
lessly having reached these during times of flood. It, however, was 
not found abundant, except in a very few ponds and swamps. The 
common local practice of usmg Gambusia for bait for larger fish 
without doubt resulted in keeping the top minnow from becoming 
more abundant. Then there were certain ponds with insufficient 
shallow water to provide protection for the minnows from larger 
fish, and in at least one instance a lake had become greatly over- 
stocked with predacious fishes, so that there was a great dearth of 
food. This lake is situated in Allen Park, within the city of Augusta. 
It had been artificially stocked with large-mouthed black bass, 
locally known as ‘trout,’ in addition to several species which 
probably reached it during floods. Bass of 3 inches and upward in 
length were almost constantly present in very shallow water, preying 
on the top minnows. Sunfishes were also present in the shallow’ 
water, but it was not observed that they actually fed on the minnows. 
In August it was quite evident that fewer Gambusia were present 
in this lake than there were in April, notwithstanding the fact that 
approximately 18,000 minnows had been introduced from other 
sources during the intervening months. Other ponds apparently 
well stocked with sunfishes and bass, and which certainly did not 
offer better protection for the minnow than the lake in Allen Park, 
were stocked with Gambusia, but in none of these did such disastrous 
results ensue. In Allen Park all fishing was prohibited, while in tho 
other ponds there was a limited amount of hook and line fishing. 
The entire prohibition of fishing in Allen Park doubtlessly accounts for 
the great abundance of predacious fishes, and the shortage of food 
made it necessary for the fish to venture into shallower water than 
they ordinarily do in search of food. Later when an effort was 
made to give Gambusia a chance of survival in Allen Park, it was 
learned that the shortage of food was so great that cannibalism had 
undoubtedly prevailed. 
The following experiment shows that the common local species of 
sunfishes are not serious enemies of Gambusia. It, therefore, is 
quite certain that the bass was the chief enemy of the minnow in 
Allen Park. An old pond, measuring about 75 by 50 feet, with an 
average depth of approximately 5 feet, was stocked during the first 
week of April with about 3,000 sunfishes. Probably about 90 per 
cent of the fish were bream, Lepomis incisor (Cuvier and Valen- 
ciennes), and the others were warmouth and a few of other species. 
