CHAPTER EIGHT 



3*S 



The Microscope in Aquarium Work 



Aquarium work in general and fish breeding in particular can be 

 made both more interesting and more successful by the use of a micro- 

 scope. For most purposes a very cheap instrument is satisfactory. In 

 fact, a low power lens is preferable to a high in examining water for 

 microscopic fish food. 



All aquaria contain various beautiful and highly interesting forms of 

 microscopic life, some harmful, some negative, but mostly beneficial to 

 fishes. The constant changing of varieties and quantities presents a vast 

 field for new study, but we are here mostly concerned with the practical 

 points of raising young fishes. On page 78 we refer to the use of infusoria 

 as food. To determine the presence of this food, touch the tip of the 

 finger lightly to the surface of the water, preferably to the side nearest 

 the source of light. This is because they are mostly at the surface and 

 they seek the light. Place this drop on a glass slide and observe under 

 a good magnifying glass or a low-power microscope. The latter is rather 

 preferable, as the focus can be changed as required, and it is fitted with 

 a mirror to facilitate observation. In the absence of a microscope the 

 small pocket folding lens known as a "thread counter" will do. In using 

 this the frame of the counter should be laid directly on the glass contain- 

 ing the drop of water, and the whole placed over a mirror held at the 

 proper angle to reflect light upwards, but too strong a light should not 

 be used. A little experimenting will soon show the best light to work by. 



The creatures which are of value as food to newly hatched fishes are 

 generally of a size just too small to be detected by the naked eye, or at 

 most they look like specks of dust. At the same time they are plainly 

 observable under a good magnifying glass or low-power microscope. There 

 is a great deal of life in the water of a smaller size than will be shown 

 in this way and which probably has no food value to fishes. The high- 

 power microscope would show many of these organisms and thus be apt 

 to deceive the inexperienced observer as to the actual food value contained 



