21 



There is, no doubt, a more rapid accumulation of car- 

 bonic acid i^as and other deleterious gases in the water. 

 There is the difficulty of providing suitable food. There is 

 also the delicate nature of tishes to contend against ; the fun- 

 gus growths which infect them wherever scratched or bruised, 

 or in weak or diseased condition, and the numbers of parasites 

 infesting them, some of which are very destructive. 



And yet, upon a fair examination, it may be said that, 

 in the present state of our knowledge, the handling of fish, or 

 the keeping of them in captivity, is probably attended with 

 but little, if any, greater mortality than is usual in the keep- 

 ing of any but domestic animals. And even among do- 

 mestic animals the ravages of epidemics are frequent, and 

 the unaccountable deaths occur at times in quite as great 

 a proportion as ever occur among wild animals in captivity. 



The fact that some species of animals are more amenable 

 to the conditions of captivity than others, and that the 

 same is true of the individuals of a species, is, of course, 

 generally understood ; but it is not usually recognized in 

 such a way as to make the knowledge of practical value 

 by providing for each the conditions necessary for their 

 comfort and happiness. We recognize this necessity in 

 providing for our pet animals or our stock, because this is 

 a matter that comes home to the individual ; but in our 

 aggregations of animals for purposes of exhibition or obser- 

 vation, through a false economy generally, or, perhaps, 

 often through ignorance of the real necessities (for such 

 work is often taken up by inexperienced persons), we 

 provide what may be called comfortable prisons for the 

 confinement of animals whose natures chafe at all restraint, 

 and whose natural instincts are thus wholly checked and 

 thwarted ; the sexual instinct, that of migration, hiber- 

 nation, the variation of food and temperature, and, in the 

 case of certain fishes, perhaps, a necessity for a change of 

 character of water — fresh, salt, or brackish, as required — 

 and the activity possible in greater space, etc. 



