Plants In The Aquarium
( Originally Published 1923 )
Although the popular acceptance of the aquarium is a contrivance for the purpose of keeping fish, yet the fact is that plant growth is essential for the proper balancing of the life in the tank. Thus the aquarium becomes an appropriate adjunct to the house plants and window garden. The plants maintain the supply of oxygen in the water that is necessary for the life of the fish, and the pleasure to be derived from watching the growth of the animal and plant life together in a properly balanced aquarium opens up a different field of interest to the plant lover.
There are in fact comparatively few plants for growing in an indoor aquarium, but they differ so radically from the usual potted window plant as to create a new world, as it were. In the ordinarily small tank only two or three Of the commoner things are to be usually found, particularly eel-grass, watermilfoil, and fanwort. The fanwort alone is the most suitable plant for a very small aquarium where there is no room for variety.
But first a word as to the aquarium itself.
Generally speaking, the properly equipped aquarium consists of a rectangular glass tank, one corner of which holds a small piece of glass puttied to its side making a place for refuse. A rich alluvial soil in which the plants may flourish is a prime essential. This is so placed in the aquarium as to slope gently toward the refuse corner. And over it a layer of perfectly clean sand is placed, which pre-vents the water from being discolored. How-ever, before being put into the aquarium the sand must be thoroughly washed. Take a shallow pan, place a handful of sand in it and hold over a faucet so that a small stream of water stirs up the sand vigorously; gently rock the pan, allowing the floating particles of dust and dirt to escape over the rim. Keep repeating this process until there is sufficient cleansed sand to make a layer approximately an inch thick in the aquarium.
Most plants will not, as a rule, remain green after transplanting, therefore it is best to use the tips, for only that part of the plant which has grown in the aquarium will retain its color. This is true of water-weed (Elodea), fanwort (Cabomba), mud-plantain (Heteranthera), water-milfoil (Myriophyllum), and others. A few of these plants are usually bunched together and placed in a hole bored in the sand so that they project upward only half an inch, the sand being firmly pressed down around them. Eel-grass (Vallisneria) and arrowhead (Sagittaria) are cut back to with-in an inch or two of the roots and then placed in the finger bored holes. Plant only half of the aquarium, leaving the side containing the refuse corner free.
Water may now be poured into the aquarium. First place a sheet of paper over the refuse corner to prevent the sand from being disturbed, and then gently pour the water upon the paper until the tank is about one third full. The remainder of the water may be siphoned in with a small rubber hose, a bucket of water being stood on the edge of the aquarium to facilitate this operation.
Within two or three weeks, the vegetation has made roots and the plants will have grown a little, and fish may then be placed in the aquarium. A convenient method of computing the number of fish an aquarium will hold is to allow a quart of water for every fish two inches in length. The tank must stand in or near a window where there is plenty of light.
Fish bowls, commonly called "goldfish bowls," are the worst possible containers in which fish can be kept. They are in reality veritable torture bowls. These tanks are provided with but one small opening which keeps the carbon-dioxide in the water so that it quickly accumulates; moreover, this small opening prevents a sufficient quantity of oxygen from filtering through the water to counteract, to any extent, the carbon-dioxide gas. The one or two sprigs of greenery usually found in these bowls are more ornamental than of any practical use. Carbon-dioxide is used by the plant in the process of making food. During this process—which takes place only in the daytime—oxygen is given off as a waste product. At night the plant uses for respiration some of the oxygen which is produced by day. Now it can easily be conceived that since no plant grows in these goldfish bowls, carbon-dioxide is the prominent gas in the water. This is the reason why the fish in-variably stay near or at the top of such torture bowls, gasping for air at the surface. And they are slowly asphyxiated.
Another reason for the rapid death of the fish in these bowls is the fact that a continual changing of water is necessary to keep the water fresh, pure, and clear. This is done away with entirely in the oblong aquarium where plants are grown. The only thing necessary in such a balanced aquarium is occasionally to add water to counterbalance evaporation.
Available aquarium plants may be procured either from aquarium fish specialists or from such florists and nurserymen as specialize in aquatic plants for outdoor water gardens (i. e., water lilies, lotuses etc.) Those generally listed include the following:
Arrowhead (Sagittaria natans); Canadian water-weed (Elodea canadensis); eel-grass (Vallisneria spiralis); fanwort (Cabomba caroliniana); floating moss (Azolla caroliniana); Frog-bit (Hydrocharis morsus-ranae); mud plantain (Heteranthera) ; umbrella grass (Cyperus alternifolius); pond weed (Potamogeton crispus); water aloe (Stratiotes aloides); water lettuce (Pistia stratiotes) ; water milfoil (Myriophyllum heterophyllum) ; water poppy (Limnocharis emarginata) ; water purslane (Ludwigia palustris); Water star-wort (Callitriche verna) ;Water violet (Hottonia palustris).