138 MARINE AQUARIA 



these from drinking-water concerns. If possible the water should be 

 taken from several miles out at sea and not near the mouth of any large 

 river. Clear seawater may be stored indefinitely in carboys in a subdued 

 light, although it would be better to first filter it to remove the larger 

 microscopic life. 



Evaporated sea salt, if dried in enamel or glass pans, is the next best 

 substitute for ocean water. In re-dissolving the salt, measure the strength 

 by hydrometer readings. 



Synthetically-made seawater has not been very successful. It con- 

 tains 663 grams sodium chloride, 75 grams magnesium chloride, 50 grams 

 magnesium sulphate, and 15 grams potassium sulphate; all dissolved in 

 25 litres of water. 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. 



Clearing 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 120) and, after settling, 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 125 is very 

 desirable for the marine aquarium. 



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 tem- 

 perature of 62 degrees F., but in the confines of an aquarium they will not 

 prosper in the lower temperatures. Tropical fishes are happy in a temper- 

 ature ranging from 68 to 75 degrees. Some of them can succeed when it 

 is even warmer, but it becomes difficult to satisfactory oxygenate the 

 water. 



Fishes and other marine animals of the temperate zone prefer a range 

 from 55 to 68 degrees. It will be noted that the tropicals and temperates 

 meet at 68 degrees, so if the attempt is made to mix them, this is the 

 temperature that should be closely adhered to. 



Collecting Specimens. The best places for collecting a miscellaneous 

 assortment of marine animals are the back bays, pools, pockets, marshes 

 and small streams where the ocean overflows at high tide and recedes 

 from at low. Rocky coasts furnish particularly fertile fields for the 

 aquatic hunter, and those of New England offer rich attractions in 



