234 TROPIC AL FISHES AND AQUARIA 



expands and so reduces this passageway, and vice versa. It is a very 

 ingenious and effective device and may be obtained from makers of 

 scientific glassware at small cost. Those selling them are glad to give 

 complete instructions regarding regulation, etc. 



The modern method of heating individual aquaria is by use of 

 specially designed electrical units placed in the water and controlled 

 by a thermostat. Several of these are advertised in the aquarium maga- 

 zines. We suggest the avoidance of any design in this or other apparatus 

 which brings aluminum into contact with water for lengthy periods. 

 It is not very poisonous, but it disintegrates. 



Electric light bulbs in the water are good heating units. Submarine 

 sockets are made for immersing the whole light, or the ordinary socket 

 may be used by immersing only about two-thirds of the bulb. The latter 

 is one of the best ways of applying extra heat in an emergency, or for the 

 heat treatment for certain fish diseases. The amount of heat can be regu- 

 lated by the depth to which the bulb is submerged. 



Shipping Tropical Fishes. It is doubtful policy taking risk of ship- 

 ping tropical fishes when the weather is not settled and warm. They may 

 keep warm during the train travel, only to receive a fatal chilling in 

 delivery. To guard against this some shippers have designed special 

 boxes equipped with an extra outside shell, the intervening space being 

 filled with insulating substance, Celotex board being excellent for this 

 purpose. A simple expedient consists of a tin can (with a tight lid) or 

 glass jar set in a wooden box, then completely enclosed with ground cork, 

 sawdust, papers or other substance, and the lid fastened down. The top 

 of the box should be boldly marked, stating contents. A handle on the 

 top will help keep the top side up. Some dealers guarantee safe delivery. 



Large Thermos cans, properly protected, have been successfully used 

 in shipping tropicals long distances. 



The best method of transporting tropicals, where it does not interfere 

 with interstate laws, is to get in touch with a Pullman porter and have him 

 carry them through in jars, packed in a grip. Ventilation is unnecessary. 



Aeration in Tropical Aquaria. Although plants have the same 

 beneficial effect on the water of tropical aquaria as those containing 

 goldfishes, many aquarists interested only in tropicals have little or no 

 vegetation in their tanks. This is particularly the case with dealers, 

 who must be able to catch fishes quickly and to keep close count of 

 stock. Under such circumstances, and with the frequently added neces- 

 sity for overcrowding, mechanical aeration, practically doubling the fish 

 capacity of an aquarium, is a big advantage. Low-priced midget elec- 

 tric air pumps, combined with special liberators, deliver the air in small 

 bubbles at the bottom of the water, both oxygenating it and setting up 

 a beneficial circulation. 



