
SOME FRESHWATER AQUARIUM FISHES 

receptacle and water, much plant life and frequent changes of water being 
unnecessary. The fish is an air-breather and is not dependent upon the 
oxygen liberated by aquatic plants. It will live in temperatures to 100° F., 
but, on account of its tropical origin, succumbs to those under 38° or 40° 
F. It is of such lively habit that the aquarium should be kept covered 
to prevent its leaping out of the water. The sexes should also be separated 
except in the breeding season, as the full-grown pugnaceous male 
frequently kills its mate and will exterminate any other fish in the same 
vessel. 
The nest-building habit of this fish is most curious. Thespawnings 
occur a number of times during the season, the floating nests being formed 
of air bubbles coated with gelatinous matter expelled from the mouth of 
the male. The eggs are deposited by the female, fecundated by the male, 
carefully placed in the fairy nest and permitted to hatch, he guarding and 
caring for them until the fry make their appearance. ‘Then the nest is 
destroyed and the young fishes are carefully tended until they are old 
enough to care for themselves; the male assuming the whole duty and 
keeping the female away from the young. When of sufficient age, the fry 
should be fed with the same food as young goldfishes and later will thrive 
on the prepared fish foods together with a frequent diet of earthworms or 
small particles of raw meat and liver, though the fish prefers and thrives 
best on living food. Daphnia, small worms, young snails, gnats, small 
houseflies, moths and other insects are generally fed. 
THE STICKLEBACK 
This most interesting little fish inhabits streams which reach the ocean, 
some forms frequenting brackish and salt water. It is one of the most 
belligerent of freshwater fishes and may be bred in the aquarium, but should 

FIG, 36—Four-spined Stickleback, Apeltes guadratus 
be isolated from other kinds. Its nest-building is very interesting and 
varies considerably in the natural state. Some build upon the bottom of 
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