NATURE'S REALM. 19 
of water. They are also fully as inquisitive as 
the dogfish, and like to stay near the glass side 
of the aquarium and observe what is going on 
outside of the water. Like the rainbow darter, 
they are fond of resting on rocks or on the 
branches of water plants. In fact, I have fre- 
quently seen them lie down as a person would 
on a lounge, their head upright and their body 
resting sideways on the bottom. They are 
graceful swimmers and peaceable, agreeing 
well with other fishes. Their food is the same 
as that used for goldfish, but it should be given 
to them oftener. Being tropical fish, they are 
rather sensitive to cold, and the water in which 
they are kept should never be below 55° F., 
while 70° to go° is their favorite temperature. 
I am the first who imported this interesting fish 
to this country, and, having succeeded in breed- 
ing them, am enabled to add to the above de- 
scription of the fish their mode of reproduction, © 
The paradise fish is a nest builder to a cer- 
tafn extent. Its nest is not as complicated as 
that of the stickleback, nevertheless it is a re- 
ceptacle on which it places the eggs to be 
hatched. As soon as the warm weather ap- 
proaches the males commence fighting with 
each other for the possession of the females. 
The victor leads off his female to a suitable 
corner in the aquarium, and here their family 
life begins. The nest is constructed by the 
male. In building it he takes a position about 
an inch below the surface of the water, and fre- 
quently takes air into his mouth, which he 
ejects in the shape of little bubbles. These 
bubbles seem to be covered with some viscid 
substance, which makes them last for several 
hours. He keeps this up until a little floating 
island is formed of about six inches in circum- 
ference and one-fourth of an inch in thickness. 
When the nest has reached the sufficient size 
the female approaches and swims around him 
several times until he notices her. He follows 
her now around in a circle, immediately under 
the bubble island, and all at once, with a very 
graceful motion, he seizes her by folding his 
entire body and fins around her, at the same 
time turning himself with her over in the middle 
of the water, so that the ventral parts point 
toward the nest. Now he presses against her 
and causes the eggs to flow, which, in passing 
him, become fertilized and rise to the surface” 
This act being over, the male’s attention is oc- 
cupied by gathering the eggs with his mouth 
and placing them on top of the bubble island. 
Should one accidently fall to the bottom, he 
carries it up again immediately. When all the 
eggs are cared for the female makes her ap- 
pearance again, and repeats the operation until 
about a hundred eggs are laid. The eggs are 
of the size of a period used in ordinary type, 
and of creamy-yellow color. Thirty-six hours 
after the eggs are laid the young fish make 
their appearance. They are very small and 
have the shape of tadpoles. The father takes 
especial care of them, keeps them together and 
wards off enemies. One even attempted to at- 
tack my hand when on the side of the aquarium, 
looking upon it as an enemy coming to devour 
his little ones. During the first three days his 
object seems to be to keep his young near the 
surface, where they have abundance of air and 
where he can see them all ; after that he scat- 
ters them by blowing among them. He isnow 
seen very busy everywhere in the tank, and 
often gathers some weak ones with his mouth 
and spits them to the surface. This may be to 
instruct them how to breathe. 
As the young increase in size his duty is to 
teach them how to find their food. For that 
purpose he takes a mouthful of young ones from 
a thickly-settled place and carries them to an 
unfrequented spot where food is more likely to 
be found. In short, he has a system about 
raising a crop of children. During all this 
time the female is kept in a far-off corner. He 
does not allow her to go near the nest, although 
I have never seen a female injure any of the 
young, which were sometimes close around 
her, some even nibbling at her mouth. When 
the young are ten or twelve days old they have 
the shape of the old ones and can support them- 
selves. They are then one-sixteeth of an inch 
inlength. Atthis period the male builds a new 
nest and a new crop of young ones is raised; 
this is followed by a third and fourth, until the 
approach of cold weather puts a stop to it. 
Under favorable circumstances the paradise 
fish will attain their full growth at the age of 
one year, but five years seems to be the limit 
of their life. 
