14 GOLDFISH VARIETIES AND 
Another scavenger fish is the Sacchobranchus fossilis. This fish has 
a head like a catfish and an elongated body like an eel. Both of these 
scavengers are harmless to other fish, but should not be used when over 
five inches long as they stir up the water too much. 
Goldfish keep the sand loose and in good condition by picking it 
up in their mouths, but most other aquarium fishes do not touch it, which 
allows it to cake and become permanently dirty. The Weather-fish is 
most excellent to introduce with such fishes, even a single small one 
keeping the sand in a large aquarium loose on the top. 
Aquarium Covers. It is a popular idea that a free access of air to 
the aquarium is essential to the welfare of the fishes, but this is not so, 
particularly if there is a liberal plant growth. A glass cover, raised about 
a quarter inch, promotes a more luxuriant growth of plants, keeps the 
surface of the water free of dust or bubbles, prevents objects from acci- 
dentally falling in the aquarium, keeps the fishes from leaping out and our 
friend the cat from fishing in. Wire gauze, properly secured, will serve 
the latter purposes. 
With tropical fishes the glass cover should rest directly on the aqua- 
rium or jar, with no intervening space. This keeps the water a few 
degrees warmer. Furthermore, there are a number of tropical fishes 
which can leap through a very small opening. This they are most apt 
to do when newly placed in an aquarium or otherwise disturbed. Our 
wild native fishes have an increased tendency to leap as the breeding sea- 
son approaches, this characteristic being shared in by the single-tail gold- 
fish. 
PLANTING 
Planting is usually done directly in the sand or grit. Some aquarists 
prefer planting in miniature pots so that when it is desired to clean the 
aquarium it will not be necessary to uproot the plants. In potting plants 
in this manner a few pebbles should be placed in the bottom of the pot 
and then a layer of soil, preferably from the bottom of a pond. Spread 
the roots well into the soil and then cover with about one-half inch of 
sand, so that the earth cannot become free and cloud the aquarium water. 
As a rule, it is not advisable to use any soil in planting the aquarium 
itself. 
The first operation in planting an aquarium is to see that the sand 
or grit is thoroughly clean. This can only be brought about by a long 
and thorough washing. After the water runs clear from the sand, spread 
the bottom of the aquarium to a depth of, say, half an inch. Next fill 
with about two inches of water. Now take the roots of Sagittaria, 
