114 GOLDFISH VARIETIES AND 
For chemical reasons the salts should each be dissolved sepa- 
rately and enough water finally added to make ten gallons. Any good 
drinking water will do to mix with, although distilled water is not to be 
recommended because of its total lack of mineral content. Turk’s Island 
salt is evaporated seawater and has been successfully used by the Govern- 
ment at Washington. In mixing this or in preparing the foregoing arti- 
ficial water, the final test for strength should be by hydrometer as previ- 
ously directed. As chemicals vary in strength and in weight owing to 
different degrees of moisture, the hydrometer used in solutions of about 
60° Fahrenheit furnishes the only accurate gauge. 
Newly made artificial marine water ought not be used for several 
days, but be given a little time to ripen. An occasional stirring helps the 
process. 
Cleaning Marine Water. It is desirable to keep the marine aquarium 
crystal-clear, both for the benefit of the inmates and the pleasure of the 
observer. To this end several factors must be borne in mind. Start with 
clear water. Do not overcrowd nor overfeed. Use only subdued light. 
Quickly remove decaying plants, dead mussels, anemones, etc. Occa- 
sionally siphon off the bottom (see page 229) and after setting, pour back 
the clear water or return through filter. Very little loss of water is occa- 
sioned if the dregs are thrown away after water has settled, particularly if 
a tall jar is used. The filter arrangement described on page 233 is very 
desirable for the marine aquarium. The more pretentious establishments 
run the water off into deep filter-beds of fine sand, squirting it back into 
the aquarium under pressure to increase oxygenation. This, next to run- 
ning seawater, is the ideal arrangement, but is out of reach of the ordinary 
mortal. 
Temperature. This matter depends very largely upon the climate 
from which the aquarium inhabitants come. For this reason it is not well 
to mix animals of tropical and temperate zones. Many of the tropical 
fishes come north in summer and can successfully withstand a temperature 
of 62° F., but in the confines of an aquarium they will not prosper in the 
lower temperatures required by the fishes of our own climate. Tropical 
fishes are happy in a temperature ranging from 68° to 75°. Some of them 
can succeed when it is even warmer, but it becomes difficult to satisfac- 
torily oxygenate the water. 
Fishes and other marine animals of the temperate zone prefer a range 
from 55° to 68°. It will be noted that the tropicals and temperates meet 
at 68°, so if the attempt is made to mix them, this is the temperature that 
should be closely adhered to. 
