
208 THE FRESH-WATER AQUARIUM. 
then is the best for this purpose. This is especially true in 
the winter time, while in summer a northern aspect would 
be preferred, as the water in the aquarium is apt to be over- 
heated by the sun during the hot months. One trouble 
which arises from too much sun is this: that the small green 
plants of conferva grow very rapidly upon the qium and 
stones, obstructing Nm view of the inside of the pite and 
rendering the stones very hard to clean when taken out. 
These confervee do not injure the water at all; they even 
give out oxygen as other plants, and it seems as if it werea 
provision of nature,that they should render the glass opaque 
so as to protect the inmates of the tank from injury. This 
confervoid growth is not essential to the welfare of the tank 
if it is péunely stocked with other plants, and it is desira- 
ble to have as little as possible of it. To effect this, a wide 
screen, or a simple sheet of brown paper, so placed as to 
shut out the sunlight from the tank will answer the purpose; 
or by pulling the window shade down when the sun shines 
upon the tank; or, what is best, by placing a row of plants 
with full foliage between the tank and the window, we have 
other means of obviating the difficulty. 
Whether the sun shines upon the tank or not, a fresh-water 
aquarium should have all the daylight it can get, both for its 
own welfare and for our own convenience in examination. 
lam convinced that this is correct from my own experience, 
although Mr. Hibberd, a good authority on aquarial matters, 
says to the contrary : "A full flood of daylight is more harm 
than. good, a frequency of sunshine destructive, and the ten- 
ants of an aquarium are seen to better advantage in a vessel 
d from above only." Before any specimens are intro- 
ned. into the tank, it should be thoroughly washed out and 
the glass cleaned on all sides, as this is the only time When 
it can be done to advantage. "We are sure then that no im- 
purity of any kind will thus far hinder the success of the 
aquarium. The tank then is ready for the rock-work. This 
rock-work is useful: first, as a shelter for the animals, some 






