Aquatic JLitt 



13 



ed the nest against intruders. This was 

 the extent of her care. 



On the sixth day the eggs hatched, and 

 a like period was spent by the fry in the 

 Algae before reaching the free-swim- 

 ming stage. On the thirteenth day after 

 the deposition of the eggs the parents 

 were removed. The young grew at a fair 

 rate, reaching a length of 1^2 inches in 

 four months. A few eggs were removed 

 from the nest and incubated in another 

 tank, their development and growth ap- 

 proximating those left with the parents. 



This fish affords a fair reason why the 

 aquarist should use scientific names in 

 preference to common ones. In the 

 genus three species and one subspecies 

 are recognized ; the American U. limi, 

 U. pygmaea and U. pygamaea bilineata, 

 and the Austrian U. krameri. To these 

 are applied indescriminately at least five 

 common names : Mudfish, Dogfish, 

 Mud Minnow and Mud Trout. There 

 are several rockfish and several dogfish, 

 and the species are not related to the 

 trouts. Mud minnow is most acceptable. 



An Aquarium Heater 



HERBERT M. HALE, South Australian Museum 



The winter in Australia is generally so 

 mild that many sub-tropical fishes may 

 be kept in open ponds all the year round. 

 Occasionally, however, the temperature 

 even indoors falls below the danger 

 point for some of the more delicate exo- 

 tics, and a means of heating the aquar- 

 ium becomes necessary. 



The apparatus, which I have used with 

 great success, consists of a small copper 

 heater from the top of which a pipe (the 

 outlet), leads over the edge of the aquar- 

 ium into the water; another pipe (the 

 inlet), arises from near the bottom of the 

 aquarium and enters the lower part of 

 the heater. By sucking at a rubber tube 

 temporarily attached to the shorter pipe 



whilst under water the whole apparatus 

 can be filled. The lamp or gas can then 

 be lighted under the heater. Gas, reg- 

 ulated by the thermostat described in 

 Aquatic Life, Volume II, Page it, is 

 quite satisfactory. As the water in the 

 heater becomes warm it is delivered into 

 the aquarium by the outlet pipe, and the 

 colder water from the bottom is drawn 

 into the heater by the inlet pipe to take 



its place. If the water in the heater boils 

 it is because no circulation takes place — 

 a condition due to insufficiently filling the 

 apparatus and leaving air in the system. 

 The heater should therefore be of the 

 shape shown, but need not be of large 

 size. 



It is not desirable that the aquarium 

 water shall be in contact with metal. 

 The outlet and inlet pipes should accord- 

 ingly be led into a narrow glass vessel 

 of greater depth than the water in the 

 aquarium. The water in this inner ves- 

 sel should be kept somewhat below that 

 of the aquarium. Whilst the circulation 

 of the system is thus confined, the heat- 

 ing properties are little diminished. The 

 advantage of this arrangement will be 



