10 AQUARIUM MANAGEMENT 



Distilled water, on account of its lack of desirable mineral con- 

 tent, is not beneficial to fishes, and, on the other hand, some natural 

 waters are so heavily charged with minerals (sulphur and lime 

 mainly) that they cannot be successfully used for aquarium purposes. 

 Ordinarily the city water is satisfactory unless an extra heavy charge 

 of germicide has been placed in it. If one has aquarium troubles and 

 the water is suspected, it is a good plan to refill the aquarium from 

 a stream known to contain fishes. 



Water exposed to the air absorbs free oxygen. The gills of a 

 fish mechanically extract this. The fish is in reality breathing air in 

 a finely divided state. The cooler the water the more oxygen it can 

 hold. Therefore, cool water can maintain more fishes than can warm. 

 Heat drives the oxygen out of water. If boiled in a bottle, quickly 

 stoppered and cooled without contact to air, it will be incapable of 

 supporting fish life. Suffocation in such water would soon take place. 



Chemical Depletion of Water. Constant absorption of minerals 

 from the water by plants and fishes makes a condition which should 

 be provided for. This can be done by the occasional addition of salts. 

 Make a mixture of three parts of evaporated sea salt (Turk's Island 

 Salt), and one part Epsom salts. About once a month a level tea- 

 spoonful to 20 gallons of water will prove beneficial. Usually the 

 fishes will greedily swallow these salts as they sink to the bottom, 

 which act as a mild cathartic with them. 



As previously stated, it is also well to add a small quantity of salt 

 to entirely new water, particularly if fishes must be placed in it at once, 

 for shipping or other purposes. This lessens the liability to disease 

 arising from bruises received in transit. 



The decomposition of plants, etc., sets up an acid condition in the 

 aquarium, which is not good for the fish and which causes most of the 

 crumbling noticed on the shells of snails. Ten drops of lime water to 

 the gallon of aquarium water will neutralize any ordinary acid con- 

 dition, but a better method is to keep a small piece of Plaster-of-Paris 

 in the aquarium. In dissolving, it neutralizes the acid, but as it only 

 dissolves under acid conditions, there is no danger of getting the 

 water too alkaline by this method. If the Plaster-of-Paris dissolves 

 quickly it is a sign of pronounced acid condition. We would call two 

 weeks a short time in which to dissolve a piece half the size of a shell- 

 bark in a 20-gallon aquarium. Pieces of gypsum will perform the 

 same function, but more slowly. Plaster-of-Paris can be made into 

 convenient pieces by mixing the powder with water into a mushy con- 

 sistency. It is then spread on a piece of clean glass to a depth of 



