HAMID
KHAN
319
HABITS AND HABITATS
Chaudhuri [1911] outlined the
necessary
characteristics of fishes to be selected for the
destruction of mosquito larvae, and Covell [1927]
enumerated certain requirements, based on
Chaudhuri's paper, as necessary for a really useful
larvicidal form. Most of these characters and
requirements are to be found in these larvivorous
forms from the Punjab. These fish are small in
size and range from 2 inches to 4 inches in length.
They are hardy and flourish both in deep and
shallow waters. They breed freely in confined
waters, such as tanks and ponds. They are able
to stand transport and handling, and have been
transported successfully to long distances. They
are difficult to catch and are able to escape their
enemies to some extent. They are worthless
and insignificant as food. Study of their stomach
contents shows that they are top feeders and
carnivorous.
Breeding habits
All the three indigenous species of larvivorous
fish mentioned above have spawned successfully
in tanks and ponds :—
Colisa, The outstanding feature of the
breeding of the family Anabantidae, to which
Colisa belongs, is the floating nest of bubbles
which they construct and in which the eggs are
placed, hatched and young tended [Innes, 1935].
The first account of the nidification of Colisa
(Trichogaster) fasciata was given by Paul Carbon-
nier in 1875, and its translation was published in
the Annals and Magazines of Natural History for
February, 1876 [Gill, 1907].
The description of the nest given by Paul
Carbonnier, as a matter of fact, applies to Colisa
lalia and not Colisa (Trichogaster) fasciata, as in
the latter the nest is not so elaborate as in the
case of the former [Innes, 1935]. Colisa lalia
spawned successfully in the aquaria at Lyallpur
and laid eggs on the 21, 27, 30 July and 5
August respectively. One pair spawned as late
as 22 October.
At Chhenawan Fish Farm, 293
nests of Colisa lalia were counted in one of the
ponds on 19 July. It was observed that all the
nests were confined to the area where weeds, such
as Hydrilla and Potamogeton, were in abundance.
Obviously, if it is desired to afford facilities to these
fish to spawn in ponds, some kind of floating vege-
tation is needed, especially during July and August,
to enable them to construct their nests.
The eggs are yellowish in colour, non-adhesive
and 1 mm. in diameter. They hatch out in 14—
16 hours, the temperature of water ranging from
84ºF. to 92º F. Mouth opens in 48 hours after
hatching and in 72 hours, yolk sac is absorbed.
Ambassis. Spawning of Ambassis, or Glass-fish,
as it is called by the Aquarists, has not been ob-
served by the author in the aquarium, but the
fish has successfully bred in tanks and ponds both
at Lyallpur and Chhenawan and its young have
been caught in September. The observations of
Innes [1935] and others show that during the
breeding time the Glass-fishes take a side-to-side
position, quivering all the while and turning to an
upside down pose, so that the eggs are discharged
upwards into fine-leafed plants at the sub-surface
in lots of four to eight until 40 or more have been
laid. The small, clear and transparent eggs hatch
out in 24-48 hours. The fry cling to plants or
sides of* other objects for two or three days, after
which they resort to an active swimming life and
grow quickly, feeding on fresh water micro-plank-
ton. [Job, 1941, 1].
Barbus (Puntius) sophore. Observations on
its spawning have been recorded from tanks at
Lyallpur and Chhenawan. It breeds in July,
August and September in any stretch of water and
without any restriction. Secondary sexual charac-
ters in this fish have been described in detail by
Mookerjee [1939]. The characteristic carmine
red colour along the lateral line described by
Mookerjee [1939] is found both in males and fe-
males : in the latter, it is not so well defined but
more or less diffused in nature. During spawning
the female is chased by two or three males. The
eggs are fertilized immediately after laying and
adhere to the sub-surface vegetation. The eggs
are like poppy seeds and slightly adhesive ; each
measures 1 mm. in diameter, but swells to 1.5
mm. by absorption of water by its outer memb-
rane. Hatching takes place within 20 hours at a
temperature of water ranging from 80ºF. to 84ºF.
and within less than a week the fry are strong
enough to search their own food.
DISCUSSION
Unfortunately, very little information is avail-
able regarding the quality and quantity of the
natural food of the fishes treated above. Sen
[1937] published an account of food of larvivorous
fishes of Bengal. The data which Sen presents
show that under natural conditions Trichogaster
fasciatus appear to depend for nourishment on
plankton organisms and filamentous algae, and
that insects form a small part of their diet. These
results differ materially from those recorded in
this paper. It is considered that Sen's technique
might be responsible for the difference. Sen did
not kill his fish as they were caught but usually
allowed two to three hours or longer to lapse
before studying their food. It is, therefore, not
surprising that he found a good portion of the food
in the gut of these fish beyond recognition,