1916. | B. SunDARA Ray: Freshwater Fish of Madras. 267 
withstand to a considerable extent foul water full of organic im- 
purities detrimental to most fish: in the city it frequently occurs 
in gutters and sewage-farms. 
Being a surface fish it is diaphanous, but possesses a remark- 
able capacity to change colour in accordance with its environ- 
ment. Fish inhabiting the Cooum river often, within a distance 
of a few yards, show variations in colour; those among green 
weeds are greenish, those in dirty water correspondingly brown 
and those in clear water translucent white; while I have caught 
specimens reddish in colour during the floods, when the water 
is brick-red owing to the admixture of clay. 
The breeding season extends chiefly from September to Feb- 
ruary or even later, but is certainly not limited to these months. 
In the Cooum the earliest specimens with eggs are found in brackish- 
water and only later in fresh water higher up. The peculiar breed- 
ing habits were first observed by Dr. Jenkins.! During the spawn- 
ing season the dorsal, caudal and anal fins in both sexes usually 
acquire a bright golden-yellow edge. The eggs after extrusion are 
attached in two rounded clusters, one on each side, to the genital 
opening of the female. In the natural surroundings the eggs are 
probably carried till they are hatched, a condition highly favour- 
able for their protection and aeration; but in an aquarium they are 
sooner or later cast and, being demersal, sink to the bottom. Gobies 
and carp attack the fish when it is carrying eggs and feed on the 
latter. On an average from 20 to 40 eggs are carried by a female 
at a time. 
Description of egg.—The eggs are transparent and large, about 
I mm.” indiameter. Under the microscope the outer egg-membrane 
is seen to give off externally numerous short adhesive threads, by 
means of which the eggs adhere to one another or to foreign objects 
(figs. 12-14). From a certain area on each egg a group of very long 
filamentous threads arise, and these from different eggs are twisted 
together to form a common cord which protrudes from the genital 
opening of the female (fig. 12). In the yolk there is a small oil 
globule, not large enough to make the egg float. The embryo is 
clearly seen within the egg-membrane in all stages of development 
(figs. 13 and 14). Inan advance stage dark pigment cells appear on 
the body of the developing embryo and the egg looks dark in colour. 
Distinguishing characters of the fry.—I succeeded in hatching 
some eggs in an aquarium. The fry when hatched measure 4 mm. 
in length and possess the pectoral fins and a single median fin start- 
ing dorsally about the middle of the back, and continued round 
the tail up to the remains of the yolk-sac on the ventral surface. 
They are easily identified from the fry of other fish by the charac- 
teristic arrangement of dark stellate pigment-spots. On the head 
and snout a few large scattered spots occur ; immediately behind 

: @ ts 
! Jenkins, Rec. Ind. Mus., V, p. 137, pl. vi, figs 7 and 7a. 
2 Jenkins, 7. c. (His measurement of the egg ‘‘ about a centimeter ’’ is obvi- 
ously wrong). 
