Mosquito Larve and Freshwater Fish. 
By DR. Rh. HANIESCH: 
The following pages contain a Report which I prepared, at the 
request of Government, upon the possible usefulness of the small 
fish Haplochilus panchax, the ‘Ikan mata lalat’ of the Malays, in 
keeping down Mosquito larvee and consequently Malaria, as the 
fish ‘ Millions’ of Barbados is said to do. 
The island of Barbados enjoys a remarkable immunity from 
fever, and two or three years ago, when the reason of this.was put 
down to the presence in enormous numbers, on the island, of a 
certain fish which feeds on small crustaceans and insects, including 
mosquito larvee, the Colonial Office decided to try the experiment 
of distributing that fish among the various tropical Colonies, to 
ascertain if it might be of any service in checking Malaria in other 
places as well. This fish, the ‘Millions’ (Girardinus poaciloides, 
de Filippi *), so called on account of the enormous numbers in 
which it occurs in Barbados, is only a small species, according to 
Giinther, about 1$ inches in length, and belongs to the family Cypri- 
nodontide. 
The Zoological Society of London, together with the Agricul- 
tural Department of Barbados, declared itself willing to help in 
the experiment and in the distribution of the Fish, though there 
was some scepticism as to whether.the experiment would be a suc- 
cess.t However, as a closely allied fish, Haplochilus panchaz, the 
‘Tkan mata lalat’ of the Malays, occurs in the Malay region, it 
was thought that before introducing here the Millions’ of Barba- 
dos, it should be ascertained whether the Haplochilus panchax 
might not be as effective in checking Mosquito larve, and I was 
accordingly asked to investigate the matter. 
RAFFLES MUSEUM AND LIBRARY 
SINGAPORE. 
15th May, 1912. 
To the Hon’ble The Colonial Secretary, S.S. 
Sir, 
In accordance with your minute of 21-3-1912 (H. C. 2943) I 
have the honour to submit herewith a Report on the distribution 
and habits of the fish Haplochilus panchazx, H. B. 
(oF 
* Giinther (Brit. Mus Catal. Fishes, Vol. VI, p. 856) and D. S. Jordan and 
B. N. Evermann (The Fishes of North and Middle America. Vol. I, p. 689) refer 
to it under the name Lebistes peciloides. 
t See letter of Captain J. A. M. Vipan in Proccedings, Zoological Society, 
1910, pp. 146-147. 
Jour. Straits Branch 
