234 . TREUBIA VOL. Il, 2—4. 
later it swam about again quite cheerfully, albeit with the caudal fin stuck 
together and one of the pectoral fins half-shrunken. 
In MENSE’s Handbuch der Tropenkrankheiten, Band V (5) and in a 
publication by WILSON (*”) of the Madras Fisheries Bureau, species of 
Haplochilus, among which also Haplochilus panchax, are frequently mentioned 
among the best destroyers of mosquito-larvae and pupae. According to 
SEYMOUR SEWELL and CHAUDHURI (*°) there are among eleven different 
“Indian fishes of proved utility as mosquito-destroyers”, three species of 
Haplochilus, among which Haplochilus panchax is “by far the most useful 
for the purpose of destroying mosquito larvae”. It even appeared from 
comparative experiments that these Maplochilus species are even far better 
mosquito-destroyers than the famous “millions” (Girardinus (s. Lebistes) 
poeciloides DE FILIPPI) of Barbados. 
Further down in the same publication they say: “it is difficult to realise 
how anyone who has studied the animal” (i.e. three species of Haplochilus, 
among which Haplochilus panchax) “in its native haunts, or has watched 
it feed on the larvae in captivity can avoid becoming convinced that it is 
or may be a very important factor in the reduction of the numbers of 
mosquitoes bred in any given area of water”. 
At the laboratory I found how many kepala timah kept in small 
aquaria always fall to eagerly on the mosquito-larvae and -pupae on which 
they are daily fed. With this nourishment a couple of kepala timah lived 
and grew for a year in a small stopper-jar, and only died at last in 
consequence of an outward circumstance which had nothing to do with 
nutrition, and might have been avoided. 
In order to ascertain what the kepala timah in the empangs feed on, 
I have examined the contents of the intestinal tract of a large number !) 
of specimens immediately on their being caught. I regularly found in it: 
larvae and pupae of Anophelines, 
larvae and pupae of other Culicidae, 
larvae of Chironomidae, 
Hydroporinae, 
water-bugs, especially young Sphaerodema’s, 
small Jarvae of Odonates, 
little aquatic shell-bearing Gastropods, 
Cladocera sometimes in very large numbers, 
Copepods, 
Gammaridea, 
Spiders, 
once Nereidae, | 
and further frequently ants which had probably fallen into the water along 
the edges of the ponds. The hard skeleton of the head of Anopheline- 
1) more than a hundred. 
