CARE AND FEEDING OF LABORATORY FISH 



347 



oxygen or where the light is insufficient to maintain the plants. Artificial aeration is 

 particularly harmful to fish fry which are extremely delicate and are damaged by the air 

 bubbles and excess currents of water. (See Downing and Truesdale 1956) 



ACUARIUM LIGHTING: 



The most uniform lighting is that from the northern skies, without direct sunlight. 

 Aquaria may be exposed to direct sunlight but for not more than 1 hour each day. Con- 

 tinuous artificial lighting may upset the normal fish cycles since many fish actually sleep 

 and some seem to carry on maturational processes during the night and oviposition dur- 

 ing the day, e. g. , Oryzias. The best conditions are attained if the background behind 

 the tank is light (white cardboard) and a 50-75 watt bulb is placed above and toward the 

 front of the tank with reflector throwing the light toward the back of the tank away from 

 the observer. The bulb should be at least 8-12 inches away from a 5-gallon tank and the 

 light should be on for an 8-hour day. For fluorescent light use only warm, yellowish or 

 white tubes, not daylight tubes. If the aquarium becomes discolored with an abundant 

 growth of algae, reduce the light ration. 



AQUARIUM VEGETATION: 



The plants that are used in fish aquaria have three functions, to provide a means of 

 achieving chemical balance, to aerate, and to add beauty. Unfortunately the last function 

 is generally the only one considered. 



The plants should not be dropped into the tank but should be spaced appropriately. In gen- 

 eral, the two back corners should have abundant gravel (or sand) and the taller (Sagittar- 

 ias) plants carefully placed. See that the roots are completely covered in the non-floating 

 plants. The smaller plants rrray be placed in the back center, leaving the front of the tank 

 free. This will facilitate cleaning (with siphon), will space the plants properly so that 

 they will be exposed to light and give off oxygen, and w ill also provide an artistic back- 

 ground for the fish. 



The type of plants to use depends upon a number of factors such as the size of the tank, 

 the amount of oxygen needed, and whether the plants are to be used for hiding of female 

 (Betta) or fish fry. A list of plants is given below but it must be remembered that all 

 plants should be sterilized before placing them in an aquarium. This sterilization is 

 accomplished by washing them in a dilute solution of potassium permanganate for 10 min- 

 utes and then rinsing them in clear water for an equivalent period. (See Atz 1950) 



Courtesy General Biological Supply House, Inc. 

 Chicago Illinois 



