AFRICAN FISH 411 
very well as eaters of larvae. I look with favor upon using these fish wherever 
wecan. It saves considerable expense. When we get these fish in a suitable pond 
all we have to do is to keep the edges clean from grass and refuse so that the 
fish can get at them.” 
It does not appear that the “ millions ” have been tested on a large scale in the 
Canal Zone, and perhaps with the large scale topographic changes in progress 
there this is impossible. Recently J. A. M. Vipan has shown that no far-reach- 
ing results can be expected from the introduction of Girardinus peciloides on 
the American mainland. Vipan states that the extraordinary abundance of 
these fish in the island of Barbados is due to the fact that no other fresh-water 
fish exist there to keep them in check. He points out that furthermore Girar- 
dinus peciloides is already indigenous in some of the regions in which its in- 
troduction has been attempted and that other species of fish exist there which 
are equally efficient destroyers of mosquito larve. The reason why these fish 
do not multiply in the same degree as in the small islands of the Antilles is that 
they are preyed upon by other species of fish. 
A BRAZILIAN FISH. 
Excellent results are obtained in Rio de Janeiro, Brazil, by the use of a small 
fish known as the “barrigudo” (G@irardinus caudimaculatus) which feed on 
the larve of mosquitoes most voraciously. In the great prophylactic work 
carried on in that city under the public health service, it is placed in tanks and 
other receptacles where it is impossible to use petroleum. 
AN AFRICAN FISH. 
Mr. J. Vosseler, in an article entitled “ Fische als Moskito-Vertilger,” pub- 
lished in “ Der Pflanzer, Ratgeber fiir Tropische Landwirtschaft,” for June 13, 
1908, vol. 4, No. 8, pp. 118-127, gives an interesting account of some experi- 
ments with mosquito-feeding fishes in German Hast Africa. He brings out 
the point that on account of the great physical and chemical differences in 
the water inhabited by mosquito larve the selection of suitable species of fish is 
made difficult by several restrictions. He states that the shallow shores of rivers 
or large lakes can be excluded from consideration, since the young of most 
species of fish living there frequent the shores in shoals, and prey upon the 
various forms of animal life, mosquito larve included. Many water supplies, 
however, contain salt and other chemicals, and are polluted from various sources, 
even from the excrement of game coming to drink, while temporary collections, 
such as pools, puddles, irrigation ditches, contain turbulent muddy water. The 
level of the water in these different conditions is very variable, and the tem- 
perature of the water goes through great variations within a single day ; often 
at the midday heat rising above the limit which most fishes can stand. A fish 
which would withstand all these conditions would be very exceptional. In 
considering the question of fish introduction, the capability of the species for 
acclimatization, its power of enduring long transportation, and its ability to 
multiply rapidly, even under adverse conditions, are of vital importance to 
