WATERS AND HOLDING PROCEDURES Q 



tion between members of the same genus appears to 

 occur. 



Both the number produced and survival of guppies 

 has been shown to be controlled by an inhibitor. 



We might now make some generahties on aquarium 

 management that take into consideration the fore- 

 going information. New water should be used for 

 flushing aquaria and for making aged and condi- 

 tioned water. Aged water is ideal as an environment 

 for young fishes of aU species. In the culture of many 

 fishes aged water for fingerlings is considered a neces- 

 sity. For small species of fishes that utilize the tiny 

 plants and animals contained in aged water, aged 

 water would be of value for flushing tanks. 



Conditioned water is a matter of concern in growth 

 studies. In this type study the initial filling of the 

 aquaria should be with conditioned water. It is pos- 

 sible that only a part of the water need be condi- 

 tioned, i.e., a tank might be fiUed with new or aged 

 water and then a portion of conditioned water added. 



The primary concern with polluted water is the 

 development of aquarium management procedures 

 that avoid the accumulation of putrescible materials. 

 As pointed out above, food and fecal material are 

 normally the principal source of trouble. Fecal ma- 

 terial should be removed by periodically siphoning 

 off the bottom of the aquaria. Trouble from food is 

 avoided by not overfeeding and by the selection of a 

 food that is not too rapidly soluble in water. Some 

 foods, as for example, ground Hver, are very trouble- 

 some to feed, while Hve foods such as water fleas 

 (Daphnia) and brine shrimp (Artemia) seldom pro- 

 duce a pollution problem. Ammonia and other gases 



