20 



THE AQUARIUM. 



who seek to rob him of his meal. Three or four fish will 

 seize it at once, and the excitement that ensues as each 

 pulls in a different direction is most amusing to the 

 spectator. 



As an instance of their extreme hardihood we may 

 mention that we have kept a number of them in a tank 

 in the open air, exposed to all weathers. This fact in 

 itself is of little importance, for in ponds they are ex- 

 posed to similar conditions. But there is this difference. 

 In the deep waters of the ponds they can swim freely 

 below the ice in the hardest winter, but in our tank 

 during the Arctic weather of the past winter (1881) the 

 water was frozen into a solid block of ice. Whether the 

 fish found a small unfrozen cavity at the bottom, or 

 whether they were frozen up in the ice, we cannot say, 

 but we had given up all hopes of seeing them alive again. 

 On the third day after the thaw we visited the tank, and 

 found that only about half-an-inch all round the block 

 had melted. The fish had found their way into the open 

 channel thus formed, and thence on the surface of the 

 block, which was covered by about one-eighth of an inch of 

 water. In this the fish, almost worn out, were kicking 

 and struggling on their sides, unable to get back to the 

 deeper channel. We removed some of them to an in- 

 door aquarium, where they soon exhibited the greatest 

 liveliness, and have not since shown any evil results 

 arising from the freezing process they must have under- 

 gone. 



The foregoing species may all be kept with tolerable 

 success in still water, but if the aquarium-keeper would 

 have Dace, Roach, or Gudgeon, he must have a stream 

 of constantly-flowing water. They are inhabitants of 

 swift-flowing streams, and cannot brook the stillness of 



