GOLDFISH VAEIETIES AND 



installed at moderate cost. These are extremely vauable in guarding 

 against the dangers of sudden cold spells at night, particularly where 

 tropical fishes are kept or when young goldfishes have been hatched in 

 the late winter or early spring months. Oil stoves are not to be recom- 

 mended and should only be used in emergencies. The carbonic product 

 of combustion while small in quantity is, nevertheless, injurious. Water 

 absorbs most gases very freely. 



The cement floors of fish houses should be provided with gutters next 

 to the tanks, these all draining to a single point so that the floors can 

 easily be flushed down. 



A description of methods of building concrete ponds and tanks will 

 be found on page 220. 



Commercial Breeding of Tropical Fishes. The detailed descriptions 

 of breeding habits described on pages 92 to 100 will give a practical 

 working basis for anyone wishing to enter this field commercially. There 

 are, however, a few generalizations which ought to be of value here. In 

 Nature the fishes manage to reproduce themselves without the help of 

 man. The three principal reasons are because they have water of the 

 proper temperature, food of the right character and plenty of opportunity 

 for the young to hide. All of the conditions can be produced artificially. 

 The European breeders use tubs, introduce a thick growth of plants, place 

 in one or more pairs of breeders as occasion demands, feed plenty of 

 daphnia, mosquito larvas, etc., and disturb the fishes as little as possible. 

 In the absence of greenhouses the tubs are sunk in the ground, covered 

 with wire netting in warm weather and with glass on cool nights or days. 

 Quite large tanks are sometimes used, placing different species with the 

 same breeding habits together, not attempting to sort out the various young 

 until fall. In the livebearing groups there is no likelihood of hybridization 

 if males and females of the same species are both present. Some fishes do 

 not like plants and will tear them out (cichlide group, for instance), but 

 as a rule the young very early appreciate their value and quickly hide 

 among them. They also hunt sloping, shallow edges where the larger 

 fishes cannot follow, particularly if Salvinia or other small floating plants 

 are along the edge. 



A continuous, warm temperature is imperative for some species and 

 for these it is not worth while attempting to breed outdoors in a temperate 

 climate. 



In selecting a stock to breed from for commercial purposes it is 

 inadvisable to choose the species which have already become common, even 

 though they are easy to breed. It is much better to pay more for some- 

 thing out of the ordinary if there seems to be a reasonable chance of 

 breeding it. The "fashions" change so rapidly in tropical fishes that we 

 could not attempt here to advise what to breed, as our book would be likely 

 to look old by the time it is off press. 



