320
Relative Value of Certain Larvivorous Fishes from the Punjab
because digestion and disintegration of the food
continued in them. Further, Sen did not conduct
the investigations on the food of these fish for the
whole of the year, but based his conclusions on
the results obtained from a study for a month or
so 1 . Sen's methods and techinque have been
previously criticized by Hora [1937].
The present investigations show that in Colisa
lalia the food consumed consists of mosquito eggs
and larvae, Dipterous larvae, Coleoptera—adult
and larvae—and a large number of other insect
larvae, which on account of their semi-digested
condition could not be identified. In addition
to the insect diet, the fish consumes Crustacea and
Rotifers in abundance. It has also been observed
that the vegetation found in the stomach and gut
of Colisa is, in many cases, that which had been
consumed by the Crustacea and Rotifers on which
the fish had fed. There is, therefore, sufficient
evidence to believe that Colisa is carnivorous in
its habit.
Ambassis, though it is an active cyclopscidal
fish, does not hesitate to consume mosquito eggs,
mosquito larvae and other insect larvae whenever
they are available.
The present investigations have, thus, fully
demonstrated the efficiency of Colisa lalia and
Ambassis baculis to destroy mosquito larvae, not
only in the laboratory but also in field. These
species of fish can, therefore, safely be recommen-
ded for larvicidal purposes.
SUMMARY
1. The larvivorous fishes of the Punjab, such
as Colisa lalia (Hamilton), Ambassis baculis
(Hamilton) and Barbus (Puntius) sophore Hamilton,
have been observed to devour in captivity mos-
quito larvae at the rate of 148, 136 and 90 larvae
per day per fish, respectively.
2. The study of their gut contents seems to
indicate that Colisa lalia and Ambassis baculis,
when introduced into a tank where mosquito
larvae are to be found, invariably feed on these
larvae. Where no mosquito larvae exist, they
feed on Crustacea, Rotifers and aquatic insect
larvae.
3. Barbus (Puntius) sophore is an active larvi-
vore in the laboratory, but, when introduced in
ponds, it mostly feeds on mud, decayed vegeta-
tion, algae and aquatic weeds and thus assist in
reducing the food of mosquito larvae.
4. In Colisa lalia, food takes two to three hours
to pass from the mouth to the anus.
5. All the three species thrive in such waters
as lie in the neighbourhood of towns and villages.
6. All the three species successfully breed in
tanks and ponds. Colisa spawns in July and
August and constructs a nest of bubbles, mixed
with pieces of weeds, in which the eggs are laid,
hatched and young tended. Ambassis too breeds
in July and August and Barbus (Puntius) sophore
in July, August and September. Sub-surface vege-
tation is needed, specially in July and August,
to enable all the three species to lay eggs.
7. The investigations have fully demonstrated
the efficacy of Colisa lalia and Ambassis baculis
to destroy mosquito larvae in tanks and ponds,
and these fish are recommended for larvicidal
purposes.
8. For immediate results 2,500 specimens of the
above-mentioned species are needed to free an
acre of water from mosquito larvae.
REFERENCES
American Public Health Association (1936). Standard
methods of water analysis. Eighth edition. New
York
Chaterjee, G. C. (1933). Relation of fisheries to the
malaria problem of Bengal. Sonar Bangla, Agrahayan
9
—(1934).
Biological control of malaria in rural
areas of Lower Bengal. Centr. Co-operat. Anti-Malar.
Soc. Ltd. Calcutta
Chaudhuri, B. L. (1911). Fish and mosquito larvae.
Cal. Med. J. 6, 457-70
Christophers, S. R., Sinton, J. A., and Covell, G. (1936).
How to do a malaria survey. Malaria Bureau, No. 6.
Health Bulletin, No. 14, 1-206
Covell, G. (1927). Anti-mosquito measures. Malaria
Bureau, No. 3. Health Bulletin, No. 11 Calcutta
Gill, G. (1907). Parental care among fresh water fishes.
Smithson. Rept. Washington, pp. 529-31
Hora, S. L. (1937). Fish and mosquito control. Current
Sci. 5, 554-6
Hora, S. L. and Mukerjee, D. D. (1938). Table for the iden-
tification of Indian freshwater fishes, with description
of certain families and observations on the relative
utility of the probable larvivorous fishes of India.
Health Bulletin, No. 12. Malaria Bureau, No. 4 Delhi
Hora, S. L., and Nair, K. K. (1938). Observations on the
nutrition of Panchax panchax (Hamilton). Proc.
National Inst. Sci. India IV 2, 245-51
Innes, W. T. (1935). Exotic aquarium fishes. Philadel-
phia
Job, T. J. (1941, 1). Food and feeding habits of the
glassfishes, (Ambassis Cuv. & Val.), and their bearing
on the biological control of guinea-worm and malaria.
Indian J. Med. Res. 29, 851-62
—(1941,
2). Efficiency of the Killifish Aplocheilus
panchax (Hamilton), in the control of mosquitoes.
Proc. National Inst. Sci. India, 7, 317-50
—(1941,
3). On the comparative efficacy and
relative costs of biological and chemical methods of
mosquito control in clean-weeded Railway Borrowpits
at Fuleshwar, Bengal. J. Mal. Inst. Ind. 4, 211-5
John, C. C. (1940). Observations on the utility of Aplo-
cheilus lineatus (Cuv. & Val.) for mosquito control.
J. Mal. Inst. Ind. 3, 67-80
1 . On an enquiry made by the author, through Dr
Hora, Dr Sen replied that 'the period of study of the fish
Panchax panchax was October, 1934, to January, 1935,
April 1935, June to August, 1935, May and September,
1936. With Esomus danricus the period of study was
November and December, 1934, as also September 1936,
while the fish Trichogaster fasciatus was studied in Sep-
tember 1936 only.