366 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1926 
pieces. The fact that this floats and can be reached on the surface 
from below, they seem to appreciate. The goldfish food made from 
crushed shrimps they will eat also, but as this soon falls to the bot- 
tom it is not so well adapted to their habits. 
The Gambusia is very tenacious of life. It does not, however, 
endure rough handling, and the gravid females are very sensitive 
to harsh usage. They should be taken from the water in a dip net, 
not a seine. According to Mr. Hildebrand “the best container for 
transferring and shipping Gambusia, undoubtedly is the Fearnow 
fish can, a patented device. Excellent results can be had by the use 
of lard cans, lard tubs and similar containers. If secondhand ves- 
sels are used, they must be thoroughly washed and scalded with hot 
water.” The water in the container should be shallow, forcing the 
fish to keep near the surface. This need indicates the undesirability 
of milk cans. When under way the less splashing the better. “The 
Fearnow can successfully overcomes splashing and is very con- 
venient, for transporting fish over rough roads.” 
Mr. Hildebrand further adds that it is usually advisable to con- 
fine Gambusia in the water from which they were caught. If this 
water is foul, it should not be used. It generally is best when 
Gambusia in confinement are to be transferred from pond water, 
for example, to water from another source, to mix the waters at 
first and accomplish the change more or less gradually. 
In establishing the mosquito fish in a new region, it is well to 
prepare a shallow pond some rods in diameter, with a lining of 
concrete to prevent leakage. So far as my experience in California 
goes, this should not be over 4 feet in depth. The pond may be 
stocked in the middle with pond lies and water plants, not set 
so densely as to smother the little fishes or to prevent them from 
readily getting about when hunting down “ wigglers.” Even Con- 
ferve (frog spittle), on which young fishes seem to feed, will help, 
but the plants need clearing out when too abundant. The sulphate 
of copper (blue vitriol), sometimes used to clear the water by 
destroying Conferve and the like, is fatal to Gambusia. The little 
fishes, however, make no objection to sewage in the water, and 
flourish in the gutters of Vera Cruz and other filthy cities in which 
open ditches take the place of sewers. 
As to the enemies of Gambusia, I have noticed but one especially 
destructive. This is the large water beetle, Dytiscus, about an inch 
long and of a shining brown color. This species entered my pool, 
and before it could be extirpated, one had killed a mother fish and 
another a goldfish. 
In a small pool in a garden a fungus once appeared, forming a 
white ring about the eye in individuals attacked. I imagine that 
bass and similar carnivorous fishes would attack the Gambusia, and 
