DESCRIPTI VE KEY TO BREEDING, ETC. 243 



POLYCENTRID.E— POLYCENTRIDS (No. 19) 



A small family of three species. Polycentrus breeds similarly to 

 Badis (see under Nandidae). Polycentropsis is said to build a bubble 

 nest similar to that of the Labyrinth fishes. It has been bred but few 

 times. 



SCATOPHAGIDiE— ARGUS FISH (No. 20) 

 The Argus Fish is an inhabitant of brackish water in India. It 

 has never been bred in this country. 



SILURID.aE— CATFISHES (No. 21) 



This group is now split up into several families, but it is left intact 

 here. Few of the species have been bred in aquaria. All are omnivorous, 

 and good scavengers. They are mostly harmless, but should not be kept 

 with long-finned goldfish. 



SOLEID.E— SOLES, FLATFISH (No. 22) 



The soles inhabit brackish and entirely fresh water. They are car- 

 nivorous and their breeding has seldom, if ever, been attempted in 

 aquaria. 



TETRAODONTIDiE— SWELL-FISHES (No. 23) 



These queer fishes are clowns in the aquarium. Two Indian species 

 have been used in aquaria. They are carnivorous and the breeding is 

 not known. 



GENERAL NOTES ON HABITS AND BREEDING 



The nature and breeding habits of the fishes listed are given in 

 condensed form under the family headings, but a few remarks that are 

 generally applicable are here presented. 



In attempting to keep more than one kind of fish or even different 

 individuals of the same species, it is always best to have all the fishes 

 the same size. Even if of peaceable disposition, large fishes are apt to 

 bully or eat little ones. 



Young tropicals are in general treated much alike. The newly 

 born live-bearers can eat fine Daphnia or powdered fishfood at once 

 and they are very easy to raise. Even considerable variation in tem- 

 perature is withstood. With the egg-laying fishes however, there must 

 be a constant temperature, particularly in the Labyrinth fishes, Cichlids, 

 etc. For Labyrinths it should be as high as 85° or 90° while for all 

 tropicals it should be 5° to 10° higher than usual. This is needless in 



