44 MAINTAINING FISHES 



solution is a balanced ration. The greatest number of 

 dietary diseases occur when fishes are maintained 

 entirely on prepared foods rather than being fed live 

 foods periodically. In a separate section the prepara- 

 tion of balanced rations is discussed. 



Mechanical Damage 



Fishes are more sensitive to mechanical damage 

 than is commonly reaHzed. Even slight abrasions may 

 result in fungal and bacterial infections. When infec- 

 tions become evident one or two days following han- 

 dHng, one should suspect mechanical damage. It is 

 probable that the more important infectious organ- 

 isms (Aeromonas among the bacteria and Saprolegnia 

 among the fungi) are usually present but normally 

 become a problem only as a result of fishes being 

 mechanically damaged or becoming weakened due to 

 an inadequate diet 



Fright and Temperature Shock 



Fishes exhibit fright as do the higher verte- 

 brates. They also tend to become accustomed to aquar- 

 ium conditions and to being fed and handled. Fol- 

 lowing capture from the wild, fishes should be left 

 undisturbed for one or two days and then disturbed 

 as little as possible for about a week. By the end of 

 this time, they will have become adjusted to their new 

 surroundings. 



Fishes are sensitive to drastic changes in tempera- 

 ture. When they are moved from one container of 

 water to another, differences in temperature should 

 be determined with a thermometer. If the difference 

 is greater than one or two degrees the fishes should 



