THE CARE OF HOME AQUARIA 43 



water by bacterial decomposition. The question, how can the 

 accumulation of dead matter be prevented, is therefore one of 

 the utmost importance. The usual means is to introduce some 

 animal that will act as a scavenger to clean up refuse matter. 

 The forms generally made use of are tadpoles and fresh-water 

 snails. A convenient rule is to supply one snail or large tadpole 

 such as the dealers ordinarily handle, to every two gallons of 

 water, that is to say three snails or tadpoles are sufficient for a 

 six-gallon aquarium. Either of these, under ordinary circum- 

 stances, will clean up waste particles of food and decayed vege- 

 tation and work over the fecal matter of the fishes, and will also 

 tend to prevent an excessive development of the microscopic 

 plants which form a green scum on the glass. The eggs of the 

 freshwater snails are eaten greedily by fishes and thus serve to 

 add to the natural food supply of the aquarium. 



If larger portions of plants begin to deteriorate, it will be 

 found best to cut them off and remove them, since if they are not 

 in good condition they will not serve for aeration, and will be- 

 come a source of danger. 



If care is taken in feeding — and a little study and experi- 

 ence in this matter is the only safe guide — no appreciable 

 amount of food need be left to decay. If, for any reason, the 

 food is not all consumed, or if there is any accumulation of fecal 

 or other matter, it may be readily removed by means of a long 

 pipette, or a rubber tube used as a siphon. For the small aquari- 

 um a pipette with an inside diameter of one-quarter to three- 

 eighths of an inch, and fitted with a large rubber bulb is most 

 convenient. In using the tube without the bulb, place the thumb 

 over the upper end of the tube while introducing it, then with- 

 draw the thumb when the tube is immediately over the sub- 

 stance to be removed. The substance will rush up the tube, after 

 which the thumb is replaced while the tube is withdrawn. A 

 special form of glass tube, with an expanded end, recently placed 

 on the market, holds a larger quantity of refuse and must be 

 inverted in order to empty it. This has some distinct advan- 

 tages over the ordinary straight tube. 



For larger aquaria the pipette is rather tedious and the 

 siphon is recommended. In either case the waste should be 

 strained through a cloth net and the water should be returned to 

 the tank rather than add fresh water to replace it. As has been 

 stated elsewhere, the less changing of the water the better, for 

 fear of introducing some new factor to interfere with the adjust- 



